:root {
  color-scheme: light;
  --ink: #182423;
  --muted: #6b7773;
  --paper: #fffefa;
  --canvas: #f2f0e9;
  --line: #deddd5;
  --sidebar: #132321;
  --sidebar-soft: #1c302d;
  --sidebar-line: rgba(255, 255, 255, 0.1);
  --blue: #3858e9;
  --blue-soft: #eef1ff;
  --teal: #0aa68f;
  --coral: #f06449;
  --gold: #dca12c;
  --shadow: 0 20px 60px rgba(23, 36, 34, 0.08);
  --sidebar-width: 318px;
  --inspector-width: 380px;
  font-family: Inter, ui-sans-serif, -apple-system, BlinkMacSystemFont, "Segoe UI",
    "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  font-synthesis: none;
  text-rendering: optimizeLegibility;
}

* { box-sizing: border-box; }
html, body { height: 100%; }
body { margin: 0; overflow: hidden; background: var(--canvas); color: var(--ink); }
button, input, textarea { font: inherit; }
button { color: inherit; }
button, a { -webkit-tap-highlight-color: transparent; }
button:focus-visible, a:focus-visible, input:focus-visible, textarea:focus-visible {
  outline: 3px solid rgba(56, 88, 233, 0.28);
  outline-offset: 2px;
}
.svg-sprite { position: absolute; width: 0; height: 0; overflow: hidden; }
svg { width: 20px; height: 20px; fill: none; stroke: currentColor; stroke-width: 1.8; stroke-linecap: round; stroke-linejoin: round; }
[hidden] { display: none !important; }

html { scroll-behavior: smooth; }
.home-page { display: none; }
html.home-route body { height: auto; overflow-y: auto; background: #f3f0e8; }
html.home-route .home-page { display: block; }
html.home-route .app-shell,
html.home-route .image-lightbox,
html.home-route .toast { display: none !important; }

.home-page {
  --home-ink: #101715;
  --home-paper: #f3f0e8;
  --home-mint: #b9f4df;
  --home-green: #153b32;
  min-height: 100vh;
  color: var(--home-ink);
  background: var(--home-paper);
}
.home-page a { color: inherit; text-decoration: none; }
.home-nav {
  position: fixed;
  z-index: 120;
  top: 0;
  right: 0;
  left: 0;
  height: 72px;
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  align-items: center;
  gap: 28px;
  padding: 0 clamp(20px, 3.6vw, 58px);
  color: #edf7f3;
  background: rgba(9, 18, 16, .78);
  border-bottom: 1px solid rgba(255,255,255,.12);
  backdrop-filter: blur(18px);
}
.home-brand { display: inline-flex; align-items: center; gap: 11px; justify-self: start; }
.home-brand-mark {
  width: 39px;
  height: 39px;
  display: grid;
  place-items: center;
  color: #10201d;
  background: var(--home-mint);
  border-radius: 12px 12px 12px 4px;
  font-family: "STSong", "Songti SC", serif;
  font-size: 21px;
  font-weight: 800;
}
.home-brand > span:last-child { display: flex; flex-direction: column; gap: 1px; }
.home-brand strong { font-family: "STSong", "Songti SC", serif; font-size: 18px; letter-spacing: .08em; }
.home-brand small { color: #8da59e; font-size: 7px; font-weight: 750; letter-spacing: .18em; }
.home-nav nav { display: flex; align-items: center; gap: clamp(18px, 2.5vw, 42px); }
.home-nav nav a { color: #b9c8c3; font-size: 11px; transition: color .2s; }
.home-nav nav a:hover { color: #fff; }
.home-nav-cta {
  min-height: 38px;
  display: inline-flex;
  align-items: center;
  gap: 12px;
  justify-self: end;
  padding: 0 15px;
  color: #10201d !important;
  background: var(--home-mint);
  border-radius: 7px;
  font-size: 11px;
  font-weight: 750;
  transition: transform .2s, background .2s;
}
.home-nav-cta:hover { transform: translateY(-2px); background: #d1faeb; }

.home-hero {
  position: relative;
  min-height: 100svh;
  overflow: hidden;
  color: #eff8f4;
  background:
    radial-gradient(circle at 77% 66%, rgba(38,139,113,.27), transparent 28%),
    radial-gradient(circle at 18% 4%, rgba(112,228,194,.12), transparent 29%),
    #0b1513;
}
.home-hero-grid {
  position: absolute;
  inset: 0;
  opacity: .2;
  background-image:
    linear-gradient(rgba(255,255,255,.11) 1px, transparent 1px),
    linear-gradient(90deg, rgba(255,255,255,.11) 1px, transparent 1px);
  background-size: 9vw 9vw;
  mask-image: linear-gradient(to bottom, rgba(0,0,0,.4), transparent 84%);
}
.home-hero-copy {
  position: relative;
  z-index: 2;
  width: min(1500px, 100%);
  min-height: 100svh;
  display: flex;
  flex-direction: column;
  justify-content: center;
  padding: 130px clamp(24px, 5vw, 80px) 128px;
  margin: 0 auto;
}
.home-kicker {
  margin: 0 0 30px;
  color: #85b8a9;
  font-size: 11px;
  font-weight: 750;
  letter-spacing: .17em;
  text-transform: uppercase;
}
.home-hero h1 {
  position: relative;
  z-index: 2;
  max-width: 1280px;
  margin: 0;
  font-family: "STSong", "Songti SC", Georgia, serif;
  font-size: clamp(56px, 8.2vw, 126px);
  font-weight: 700;
  line-height: .99;
  letter-spacing: -.065em;
}
.home-hero h1 span { display: block; }
.home-hero h1 span:last-child { color: var(--home-mint); }
.home-hero-bottom {
  width: min(690px, 58%);
  display: grid;
  grid-template-columns: minmax(0,1fr) auto;
  align-items: end;
  gap: 42px;
  margin-top: clamp(42px, 7vh, 82px);
}
.home-hero-bottom > p { margin: 0; color: #aebfba; font-size: 15px; line-height: 1.75; }
.home-actions { display: flex; flex-direction: column; align-items: flex-start; gap: 17px; }
.home-button {
  min-height: 50px;
  display: inline-flex;
  align-items: center;
  justify-content: space-between;
  gap: 25px;
  padding: 0 20px;
  border-radius: 8px;
  font-size: 12px;
  font-weight: 750;
  transition: transform .2s, box-shadow .2s;
}
.home-button:hover { transform: translateY(-3px); }
.home-button-light { color: #0d211c !important; background: #eff8f4; box-shadow: 0 15px 38px rgba(0,0,0,.16); }
.home-button-dark { color: #fff !important; background: #132a25; box-shadow: 0 15px 38px rgba(13,32,27,.18); }
.home-text-link { display: inline-flex; color: #b8cac5 !important; font-size: 10px; border-bottom: 1px solid rgba(255,255,255,.25); padding-bottom: 4px; }
.home-text-link.dark { color: #27473e !important; border-bottom-color: #91afa6; }
.home-hero-orbit {
  position: absolute;
  z-index: 1;
  right: clamp(40px, 8vw, 140px);
  bottom: clamp(76px, 12vh, 140px);
  width: clamp(230px, 25vw, 390px);
  aspect-ratio: 1;
  border: 1px solid rgba(185,244,223,.17);
  border-radius: 50%;
  animation: home-orbit 26s linear infinite;
}
.home-hero-orbit::before, .home-hero-orbit::after { content: ""; position: absolute; border: 1px solid rgba(185,244,223,.13); border-radius: 50%; }
.home-hero-orbit::before { inset: 18%; }
.home-hero-orbit::after { inset: 38%; background: rgba(185,244,223,.04); }
.orbit-core { position: absolute; inset: 41%; display: grid; place-items: center; color: var(--home-mint); font-family: Georgia, serif; font-size: 22px; }
.orbit-word { position: absolute; padding: 6px 9px; color: #a9c7be; background: #10201d; border: 1px solid rgba(185,244,223,.18); border-radius: 18px; font-size: 9px; animation: home-counter-orbit 26s linear infinite; }
.word-one { top: -13px; left: 45%; }
.word-two { top: 43%; right: -20px; }
.word-three { bottom: -12px; left: 42%; }
.word-four { top: 44%; left: -18px; }
@keyframes home-orbit { to { transform: rotate(360deg); } }
@keyframes home-counter-orbit { to { transform: rotate(-360deg); } }
.home-scroll-cue { position: absolute; z-index: 3; bottom: 28px; left: 50%; display: flex; align-items: center; gap: 10px; color: #7f9992 !important; font-size: 9px; letter-spacing: .12em; transform: translateX(-50%); }
.home-scroll-cue span { width: 1px; height: 28px; background: linear-gradient(to bottom, #8ad8c2, transparent); animation: scroll-cue 1.7s ease-in-out infinite; }
@keyframes scroll-cue { 50% { transform: scaleY(.55); transform-origin: top; } }

.home-section { position: relative; padding: clamp(90px, 12vw, 190px) clamp(24px, 6vw, 96px); }
.home-section-number { color: #638078; font-size: 10px; font-weight: 800; letter-spacing: .15em; text-transform: uppercase; }
.home-section-number.inverse { color: #77958c; }

.home-courses { padding-top: clamp(72px, 8vw, 120px); overflow: hidden; color: #eaf4f0; background: #10201d; }
.home-courses::before {
  content: "";
  position: absolute;
  top: -24vw;
  right: -18vw;
  width: 62vw;
  height: 62vw;
  background: radial-gradient(circle, rgba(70, 190, 157, .18), transparent 67%);
  pointer-events: none;
}
.home-courses .home-section-number { position: relative; color: #6f9c8f; }
.home-courses-head {
  position: relative;
  width: min(1260px, 100%);
  display: grid;
  grid-template-columns: 1.25fr .75fr;
  gap: 70px;
  align-items: end;
  margin: 52px auto 58px;
}
.home-courses-head h2 { margin: 0; font-family: "STSong", "Songti SC", serif; font-size: clamp(48px, 6.2vw, 92px); line-height: 1.06; letter-spacing: -.055em; }
.home-courses-head p { max-width: 430px; margin: 0 0 9px; color: #94aba4; font-size: 13px; line-height: 1.85; }
.home-course-grid { position: relative; width: min(1260px, 100%); display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: clamp(20px, 3vw, 38px); margin: 0 auto; }
.home-course-card {
  min-width: 0;
  overflow: hidden;
  color: #15251f !important;
  background: #f4f1e9;
  border: 1px solid rgba(255,255,255,.18);
  border-radius: 22px;
  box-shadow: 0 28px 80px rgba(0,0,0,.24);
  transition: transform .3s cubic-bezier(.2,.7,.2,1), box-shadow .3s, border-color .3s;
}
.home-course-card:hover { transform: translateY(-9px); border-color: rgba(177,244,219,.56); box-shadow: 0 38px 95px rgba(0,0,0,.34); }
.home-course-card figure { position: relative; height: clamp(205px, 24vw, 340px); margin: 0; overflow: hidden; background: #e7e5dc; }
.home-course-card figure::after { content: ""; position: absolute; inset: 0; background: linear-gradient(to top, rgba(11,29,24,.62), transparent 48%); pointer-events: none; }
.home-course-card figure img { width: 100%; height: 100%; display: block; object-fit: cover; transition: transform .6s cubic-bezier(.2,.7,.2,1); }
.home-course-card:hover figure img { transform: scale(1.035); }
.home-course-card figure > span { position: absolute; z-index: 2; right: 22px; bottom: 20px; left: 22px; color: #e9f9f3; font-size: 10px; font-weight: 780; letter-spacing: .13em; text-transform: uppercase; }
.ml-course-card figure { background: #eef0e8; }
.ml-course-card figure img { object-fit: contain; padding: clamp(16px, 2vw, 30px); background: #f5f4ec; }
.home-course-card-body { padding: clamp(24px, 3vw, 38px); }
.home-course-provider { display: flex; align-items: center; justify-content: space-between; gap: 12px; color: #4e7268; font-size: 8px; font-weight: 850; letter-spacing: .12em; }
.home-course-provider em { color: #78847f; font-style: normal; letter-spacing: .04em; }
.home-course-card h3 { margin: 22px 0 13px; font-family: Georgia, "Times New Roman", serif; font-size: clamp(29px, 3vw, 45px); font-weight: 500; letter-spacing: -.035em; }
.home-course-card-body > p { min-height: 66px; margin: 0; color: #596762; font-size: 12px; line-height: 1.75; }
.home-course-card dl { display: grid; grid-template-columns: repeat(3, 1fr); margin: 28px 0 30px; border-top: 1px solid #c9cec7; border-bottom: 1px solid #c9cec7; }
.home-course-card dl div { min-width: 0; padding: 16px 10px 15px 0; }
.home-course-card dl div + div { padding-left: 16px; border-left: 1px solid #d3d6d0; }
.home-course-card dt { color: #173b31; font-family: Georgia, serif; font-size: 22px; }
.home-course-card dd { margin: 5px 0 0; color: #7c8984; font-size: 8px; }
.home-course-card-body > strong { display: flex; align-items: center; justify-content: space-between; color: #173b31; font-size: 11px; }
.home-course-card-body > strong span { width: 34px; height: 34px; display: grid; place-items: center; color: #10251f; background: #b9f0dc; border-radius: 50%; font-size: 15px; }

.home-proof { min-height: 105svh; background: #f3f0e8; }
.home-proof-statement { width: min(1200px, 100%); margin: clamp(70px, 10vw, 145px) auto 0; }
.home-proof-statement p { margin: 0 0 12px; color: #6e7773; font-family: "STSong", "Songti SC", serif; font-size: clamp(26px, 3.1vw, 48px); }
.home-proof-statement h2 { max-width: 1080px; margin: 0; font-family: "STSong", "Songti SC", Georgia, serif; font-size: clamp(50px, 7vw, 104px); line-height: 1.05; letter-spacing: -.055em; }
.home-proof-grid { width: min(1200px, 100%); display: grid; grid-template-columns: .8fr 1.2fr; gap: clamp(55px, 10vw, 150px); align-items: end; margin: clamp(90px, 12vw, 170px) auto 0; }
.home-proof-copy { max-width: 420px; }
.home-proof-copy p { margin: 0 0 22px; color: #4f5d59; font-size: 14px; line-height: 1.85; }
.home-stats { display: grid; grid-template-columns: repeat(3, 1fr); border-top: 1px solid #bfc4bd; }
.home-stats article { min-width: 0; padding: 27px 20px 25px 0; border-bottom: 1px solid #bfc4bd; }
.home-stats strong { display: block; font-family: Georgia, serif; font-size: clamp(31px, 4vw, 58px); font-weight: 500; letter-spacing: -.05em; }
.home-stats strong span { color: #83908b; font-size: .48em; }
.home-stats p { margin: 9px 0 0; color: #6b7773; font-size: 10px; }

.home-reading { overflow: hidden; color: #edf6f2; background: #10201d; }
.home-reading::before { content: ""; position: absolute; top: 0; right: -12vw; width: 48vw; height: 48vw; background: radial-gradient(circle, rgba(52,144,120,.22), transparent 66%); }
.home-reading-head { position: relative; width: min(1240px, 100%); display: grid; grid-template-columns: 1.2fr .8fr; gap: 70px; align-items: end; margin: 70px auto 100px; }
.home-reading-head h2 { margin: 0; font-family: "STSong", "Songti SC", serif; font-size: clamp(55px, 7.4vw, 108px); font-weight: 700; line-height: 1.03; letter-spacing: -.055em; }
.home-reading-head p { max-width: 430px; margin: 0 0 8px; color: #9eb3ad; font-size: 14px; line-height: 1.8; }
.home-reader-demo { position: relative; width: min(1320px, 100%); min-height: 560px; display: grid; grid-template-columns: 23% 49% 28%; margin: 0 auto; overflow: hidden; color: #1b2926; background: #e8e6df; border: 1px solid rgba(255,255,255,.2); border-radius: 18px; box-shadow: 0 45px 100px rgba(0,0,0,.32); }
.home-reader-demo > div { min-width: 0; padding: clamp(24px, 3vw, 44px); }
.demo-sidebar { color: #e7f1ed; background: #142b26; }
.demo-sidebar strong { display: block; margin: 30px 0 35px; font-size: 17px; }
.demo-sidebar i { height: 35px; display: block; margin: 8px 0; background: rgba(255,255,255,.06); border-radius: 7px; }
.demo-sidebar i.active { position: relative; background: rgba(68,197,164,.2); }
.demo-sidebar i.active::before { content: ""; position: absolute; top: 7px; bottom: 7px; left: -12px; width: 3px; background: #65d9bc; border-radius: 4px; }
.demo-document { position: relative; background: #fffdf8; }
.demo-document small { display: block; margin: 54px 0 12px; color: #3858e9; font-weight: 850; letter-spacing: .1em; }
.demo-document h3 { margin: 0 0 34px; font-family: "STSong", "Songti SC", serif; font-size: clamp(31px, 3vw, 48px); }
.demo-document p { max-width: 530px; margin: 0 0 34px; color: #52605c; font-family: "STSong", "Songti SC", serif; font-size: 17px; line-height: 1.8; }
.demo-document b { width: 100%; height: 9px; display: block; margin: 13px 0; background: #e7e8e3; border-radius: 8px; }
.demo-document b.short { width: 61%; }
.demo-question { position: absolute; right: 38px; bottom: 42px; width: 30px; height: 30px; display: grid; place-items: center; color: #fff; background: #ef674d; border-radius: 50%; font-weight: 850; box-shadow: 0 7px 18px rgba(239,103,77,.25); }
.demo-inspector { background: #f3f1ea; border-left: 1px solid #d2d3cd; }
.demo-inspector strong { display: block; margin: 64px 0 18px; font-family: "STSong", "Songti SC", serif; font-size: clamp(22px, 2vw, 32px); line-height: 1.35; }
.demo-inspector p { color: #697570; font-size: 12px; line-height: 1.75; }
.demo-inspector div { display: flex; flex-wrap: wrap; gap: 7px; margin-top: 28px; }
.demo-inspector div span { padding: 6px 9px; color: #87675d; background: #eadfd8; border-radius: 13px; font-size: 9px; }
.demo-label { color: #76938a; font-size: 8px; font-weight: 850; letter-spacing: .13em; text-transform: uppercase; }
.home-reading-modes { width: min(1320px, 100%); display: grid; grid-template-columns: repeat(3, 1fr); margin: 100px auto 0; border-top: 1px solid rgba(255,255,255,.16); }
.home-reading-modes article { padding: 34px 34px 12px 0; }
.home-reading-modes span { color: #5d8177; font-size: 9px; }
.home-reading-modes h3 { margin: 25px 0 10px; font-size: 18px; }
.home-reading-modes p { max-width: 280px; margin: 0; color: #839b94; font-size: 11px; line-height: 1.7; }

.home-path { background: #f3f0e8; }
.home-path-head { width: min(1200px, 100%); display: grid; grid-template-columns: 1.35fr .65fr; gap: 70px; align-items: end; margin: 75px auto 115px; }
.home-path-head h2 { margin: 0; font-family: "STSong", "Songti SC", serif; font-size: clamp(50px, 6.5vw, 94px); line-height: 1.06; letter-spacing: -.055em; }
.home-path-head p { max-width: 340px; margin: 0 0 10px; color: #65716d; font-size: 13px; line-height: 1.8; }
.home-module-list { width: min(1200px, 100%); margin: 0 auto; border-top: 1px solid #b8beb7; }
.home-module-list article { display: grid; grid-template-columns: 70px minmax(200px,.8fr) 1.4fr 60px; align-items: center; gap: 30px; min-height: 105px; border-bottom: 1px solid #c9ccc5; transition: padding .25s, background .25s; }
.home-module-list article:hover { padding: 0 18px; background: rgba(255,255,255,.38); }
.home-module-list span, .home-module-list em { color: #7c8883; font-size: 9px; font-style: normal; }
.home-module-list h3 { margin: 0; font-family: "STSong", "Songti SC", serif; font-size: clamp(20px, 2vw, 30px); }
.home-module-list p { margin: 0; color: #697570; font-size: 12px; }
.home-module-list em { text-align: right; }

.home-source { display: grid; grid-template-columns: .72fr 1.28fr; gap: clamp(50px, 8vw, 130px); align-items: center; min-height: 100svh; color: #143029; background: #bcefdc; }
.home-source-copy { max-width: 500px; }
.home-source-copy h2 { margin: 58px 0 28px; font-family: "STSong", "Songti SC", serif; font-size: clamp(48px, 5.6vw, 82px); line-height: 1.05; letter-spacing: -.055em; }
.home-source-copy p { margin: 0 0 32px; color: #3f655b; font-size: 13px; line-height: 1.85; }
.home-source figure { margin: 0; padding: clamp(13px, 1.7vw, 24px); background: rgba(255,255,255,.46); border: 1px solid rgba(23,66,55,.16); border-radius: 5px; box-shadow: 0 35px 85px rgba(24,78,63,.15); transform: rotate(1.2deg); }
.home-source img { width: 100%; max-height: 72svh; display: block; object-fit: contain; background: #fff; }
.home-source figcaption { padding: 13px 4px 0; color: #52766d; font-size: 8px; letter-spacing: .08em; text-transform: uppercase; }

.home-final { position: relative; min-height: 100svh; display: flex; flex-direction: column; justify-content: space-between; padding: clamp(120px, 15vw, 220px) clamp(24px, 6vw, 96px) 35px; overflow: hidden; background: #f7f4ed; }
.home-final::after { content: "知"; position: absolute; right: -3vw; bottom: -18vw; color: rgba(20,53,45,.045); font-family: "STSong", "Songti SC", serif; font-size: 60vw; line-height: 1; pointer-events: none; }
.home-final > div { position: relative; z-index: 1; width: min(1200px, 100%); margin: 0 auto; }
.home-final p { margin: 0 0 32px; color: #72807b; font-size: 12px; letter-spacing: .1em; }
.home-final h2 { max-width: 1100px; margin: 0 0 65px; font-family: "STSong", "Songti SC", serif; font-size: clamp(55px, 7.5vw, 112px); line-height: 1.02; letter-spacing: -.06em; }
.home-final footer { position: relative; z-index: 1; display: flex; justify-content: space-between; gap: 20px; padding-top: 25px; color: #73807c; border-top: 1px solid #c8cbc4; font-size: 9px; }
.home-scroll-progress { position: fixed; z-index: 130; right: 0; bottom: 0; left: 0; height: 3px; background: rgba(255,255,255,.08); }
.home-scroll-progress span { width: 0; height: 100%; display: block; background: var(--home-mint); }

[data-reveal] { opacity: 0; transform: translateY(46px); transition: opacity .85s cubic-bezier(.2,.7,.2,1), transform .85s cubic-bezier(.2,.7,.2,1); }
[data-reveal].is-visible { opacity: 1; transform: translateY(0); }
.home-hero [data-reveal]:nth-child(2) { transition-delay: .1s; }
.home-hero [data-reveal]:nth-child(3) { transition-delay: .2s; }
.home-reading-modes article:nth-child(2), .home-module-list article:nth-child(2) { transition-delay: .08s; }
.home-reading-modes article:nth-child(3), .home-module-list article:nth-child(3) { transition-delay: .16s; }
.home-module-list article:nth-child(4) { transition-delay: .08s; }
.home-module-list article:nth-child(5) { transition-delay: .12s; }
.home-module-list article:nth-child(6) { transition-delay: .16s; }
.home-module-list article:nth-child(7) { transition-delay: .2s; }

@media (max-width: 900px) {
  .home-nav { grid-template-columns: 1fr auto; }
  .home-nav nav { display: none; }
  .home-hero-copy { padding-top: 125px; }
  .home-hero-bottom { width: min(660px, 100%); }
  .home-hero-orbit { opacity: .55; right: -80px; bottom: 90px; }
  .home-courses-head, .home-proof-grid, .home-reading-head, .home-path-head, .home-source { grid-template-columns: 1fr; }
  .home-courses-head { gap: 34px; }
  .home-proof-grid { gap: 60px; }
  .home-reader-demo { grid-template-columns: 26% 74%; }
  .demo-inspector { display: none; }
  .home-source { gap: 60px; }
  .home-source-copy { max-width: 650px; }
}

@media (max-width: 620px) {
  .home-nav { height: 64px; padding: 0 15px; }
  .home-brand small { display: none; }
  .home-nav-cta { min-height: 35px; padding: 0 11px; }
  .home-hero h1 { font-size: clamp(49px, 15.2vw, 74px); line-height: 1.02; }
  .home-hero-bottom { grid-template-columns: 1fr; gap: 25px; margin-top: 45px; }
  .home-actions { gap: 13px; }
  .home-hero-orbit { width: 220px; right: -100px; bottom: 70px; opacity: .34; }
  .home-section { padding: 95px 19px; }
  .home-course-grid { grid-template-columns: 1fr; }
  .home-courses-head { margin: 58px auto 60px; }
  .home-course-card { border-radius: 17px; }
  .home-course-card figure { height: 235px; }
  .home-course-card-body > p { min-height: 0; }
  .home-proof { min-height: auto; }
  .home-proof-statement { margin-top: 62px; }
  .home-proof-grid { margin-top: 70px; }
  .home-stats { grid-template-columns: 1fr; }
  .home-stats article { display: flex; align-items: baseline; justify-content: space-between; gap: 25px; }
  .home-reading-head { gap: 32px; margin: 58px auto 62px; }
  .home-reader-demo { min-height: 440px; grid-template-columns: 1fr; }
  .demo-sidebar { display: none; }
  .demo-document { padding: 30px 23px !important; }
  .demo-document small { margin-top: 35px; }
  .demo-question { right: 24px; bottom: 28px; }
  .home-reading-modes { grid-template-columns: 1fr; margin-top: 70px; }
  .home-reading-modes article { padding: 28px 0; border-bottom: 1px solid rgba(255,255,255,.12); }
  .home-path-head { gap: 30px; margin: 56px auto 65px; }
  .home-module-list article { grid-template-columns: 34px 1fr auto; gap: 12px; min-height: 92px; }
  .home-module-list p { display: none; }
  .home-source { padding: 95px 19px; }
  .home-source figure { transform: none; }
  .home-final { padding: 130px 19px 30px; }
  .home-final footer { flex-direction: column; }
}

.app-shell {
  display: grid;
  grid-template-columns: var(--sidebar-width) minmax(0, 1fr) var(--inspector-width);
  grid-template-rows: minmax(0, 1fr);
  height: 100dvh;
  overflow: hidden;
  transition: grid-template-columns 240ms cubic-bezier(.22,.7,.23,1);
}
.app-shell.nav-collapsed { grid-template-columns: 0 minmax(0, 1fr) var(--inspector-width); }
.app-shell.inspector-collapsed { grid-template-columns: var(--sidebar-width) minmax(0, 1fr) 0; }
.app-shell.nav-collapsed.inspector-collapsed { grid-template-columns: 0 minmax(0, 1fr) 0; }

.sidebar {
  position: relative;
  z-index: 30;
  min-width: 0;
  display: flex;
  flex-direction: column;
  overflow: hidden;
  color: #edf5f1;
  background:
    radial-gradient(circle at 15% 0%, rgba(50, 178, 153, .15), transparent 30%),
    linear-gradient(165deg, #172b28, var(--sidebar) 52%, #101e1d);
  border-right: 1px solid rgba(8, 16, 15, .65);
  transition: opacity 180ms ease, transform 240ms cubic-bezier(.22,.7,.23,1);
}
.nav-collapsed .sidebar { opacity: 0; pointer-events: none; transform: translateX(-24px); }
.brand {
  min-height: 84px;
  display: flex;
  align-items: center;
  padding: 17px 18px 15px 20px;
  border-bottom: 1px solid var(--sidebar-line);
}
.brand-home-link {
  min-width: 0;
  display: flex;
  align-items: center;
  gap: 12px;
  color: inherit;
  text-decoration: none;
  border-radius: 16px;
}
.brand-home-link:hover .brand-copy strong { color: #a9f4df; }
.brand-home-link:focus-visible {
  outline: 2px solid #75dfc5;
  outline-offset: 5px;
}
.brand-mark {
  width: 42px;
  height: 42px;
  display: grid;
  place-items: center;
  flex: 0 0 auto;
  border-radius: 14px 14px 14px 5px;
  color: #10201e;
  background: linear-gradient(145deg, #94f0d5, #3ec4a7);
  box-shadow: 0 8px 25px rgba(55, 203, 170, .2);
  font-family: "STSong", "Songti SC", serif;
  font-size: 23px;
  font-weight: 800;
}
.brand-copy { min-width: 0; display: flex; flex-direction: column; gap: 2px; }
.brand-copy strong { font-family: "STSong", "Songti SC", serif; font-size: 22px; letter-spacing: .06em; }
.brand-copy small { color: #829a94; font-size: 9px; font-weight: 700; letter-spacing: .18em; }
.sidebar-close { margin-left: auto; color: #8da49f !important; }
.sidebar-body { flex: 1; min-height: 0; padding: 18px 14px 20px; overflow-y: auto; scrollbar-width: thin; scrollbar-color: #3a504b transparent; }
.sidebar-body::-webkit-scrollbar { width: 8px; }
.sidebar-body::-webkit-scrollbar-thumb { background: #354a45; border: 2px solid transparent; background-clip: padding-box; border-radius: 10px; }

.search-box {
  height: 42px;
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 0 11px;
  margin: 0 2px 16px;
  border: 1px solid rgba(255, 255, 255, .1);
  border-radius: 12px;
  background: rgba(255, 255, 255, .055);
  transition: border-color .2s, background .2s;
}
.search-box:focus-within { border-color: rgba(105, 222, 192, .65); background: rgba(255, 255, 255, .08); }
.search-box svg { width: 17px; color: #78918b; }
.search-box input { min-width: 0; flex: 1; color: #eef7f4; background: transparent; border: 0; outline: 0; font-size: 13px; }
.search-box input::placeholder { color: #6e8580; }
.search-box kbd { padding: 2px 5px; color: #718983; border: 1px solid #3b514d; border-radius: 5px; background: #152724; font-size: 9px; }

.course-summary { margin: 0 2px 17px; padding: 15px; border: 1px solid var(--sidebar-line); border-radius: 15px; background: linear-gradient(145deg, rgba(255,255,255,.08), rgba(255,255,255,.025)); }
.course-library-link { display: inline-flex; margin-bottom: 13px; color: #8ca39d; font-size: 9px; font-weight: 700; text-decoration: none; }
.course-library-link:hover { color: #b9f4df; }
.course-summary .summary-kicker { display: flex; align-items: center; justify-content: space-between; margin-bottom: 8px; color: #68d8be; font-size: 10px; font-weight: 800; letter-spacing: .1em; text-transform: uppercase; }
.course-summary h2 { margin: 0; color: #fff; font-size: 16px; line-height: 1.4; }
.course-summary p { margin: 5px 0 13px; color: #8fa49f; font-size: 11px; line-height: 1.5; }
.summary-stats { display: grid; grid-template-columns: repeat(3, 1fr); gap: 6px; }
.summary-stats div { padding: 7px 5px; border-radius: 8px; background: rgba(7,15,14,.26); text-align: center; }
.summary-stats strong { display: block; color: #fff; font-size: 13px; }
.summary-stats small { display: block; margin-top: 1px; color: #718b85; font-size: 9px; }
.skeleton-card { min-height: 84px; }
.skeleton-line { display: block; width: 55%; height: 10px; margin: 9px 0; border-radius: 10px; background: rgba(255,255,255,.08); animation: shimmer 1.4s infinite; }
.skeleton-line.wide { width: 82%; height: 15px; }
@keyframes shimmer { 50% { opacity: .45; } }

.course-tree { display: flex; flex-direction: column; gap: 5px; }
.tree-module { border-radius: 12px; }
.module-toggle {
  width: 100%;
  min-height: 38px;
  display: grid;
  grid-template-columns: 22px minmax(0,1fr) auto;
  align-items: center;
  gap: 7px;
  padding: 7px 8px;
  color: #a8bbb6;
  background: transparent;
  border: 0;
  border-radius: 9px;
  cursor: pointer;
  text-align: left;
}
.module-toggle:hover { color: #eff8f5; background: rgba(255,255,255,.045); }
.module-toggle .chevron { width: 15px; transition: transform .18s ease; }
.tree-module.open .module-toggle .chevron { transform: rotate(90deg); }
.module-toggle strong { overflow: hidden; text-overflow: ellipsis; white-space: nowrap; font-size: 14px; line-height: 1.35; font-weight: 720; }
.module-toggle em { min-width: 22px; padding: 2px 6px; color: #6d8580; background: rgba(255,255,255,.045); border-radius: 9px; font-size: 9px; font-style: normal; text-align: center; }
.module-lessons { display: none; position: relative; padding: 2px 0 7px 17px; }
.module-lessons::before { content: ""; position: absolute; left: 14px; top: 0; bottom: 10px; width: 1px; background: #2d423e; }
.tree-module.open .module-lessons { display: block; }
.lesson-link {
  position: relative;
  width: 100%;
  min-height: 42px;
  display: grid;
  grid-template-columns: 29px minmax(0,1fr) 18px;
  align-items: center;
  gap: 7px;
  padding: 6px 7px;
  color: #91a7a1;
  background: transparent;
  border: 0;
  border-radius: 10px;
  cursor: pointer;
  text-align: left;
  transition: color .15s, background .15s;
}
.lesson-link:hover { color: #ecf8f4; background: rgba(255,255,255,.04); }
.lesson-link.active { color: #fff; background: linear-gradient(90deg, rgba(37,176,146,.2), rgba(37,176,146,.06)); }
.lesson-link.active::before { content: ""; position: absolute; left: -4px; width: 3px; height: 24px; border-radius: 3px; background: #4ed4b5; box-shadow: 0 0 14px rgba(78,212,181,.45); }
.lesson-number { width: 27px; height: 27px; display: grid; place-items: center; color: #67817b; border: 1px solid #314641; border-radius: 8px; font-size: 9px; font-weight: 800; font-variant-numeric: tabular-nums; }
.lesson-link.active .lesson-number { color: #9ff0dc; border-color: #368d7c; background: rgba(57,186,157,.12); }
.lesson-title { overflow: hidden; font-size: 13px; font-weight: 620; line-height: 1.45; text-overflow: ellipsis; white-space: nowrap; }
.lesson-state { width: 7px; height: 7px; justify-self: center; border: 1px solid #58716b; border-radius: 50%; }
.lesson-state.translated { border: 0; background: #3dc5a5; box-shadow: 0 0 0 3px rgba(61,197,165,.1); }
.lesson-state.reading { background: conic-gradient(#e1aa3f var(--progress), #40534f 0); border: 0; }
.lesson-outline { margin: 3px 8px 6px 38px; padding-left: 10px; border-left: 1px solid #314741; }
.outline-link { display: block; width: 100%; overflow: hidden; padding: 5px 0; color: #78918b; background: transparent; border: 0; cursor: pointer; font-size: 11px; line-height: 1.35; text-align: left; text-overflow: ellipsis; white-space: nowrap; }
.outline-link:hover { color: #b8ccc6; }
.outline-link.level-h3 { padding-left: 9px; font-size: 10.5px; }
.tree-loading { display: grid; gap: 10px; padding: 8px; }
.tree-loading span { height: 36px; border-radius: 10px; background: rgba(255,255,255,.045); animation: shimmer 1.5s infinite; }

.search-results { margin-top: 10px; padding-top: 12px; border-top: 1px solid var(--sidebar-line); }
.search-results h3 { margin: 0 7px 8px; color: #6f8882; font-size: 10px; letter-spacing: .08em; text-transform: uppercase; }
.search-result { width: 100%; padding: 9px 8px; color: #a9bbb7; background: transparent; border: 0; border-radius: 9px; cursor: pointer; text-align: left; }
.search-result:hover { background: rgba(255,255,255,.05); }
.search-result strong { display: block; margin-bottom: 3px; color: #e5f0ed; font-size: 11px; }
.search-result p { display: -webkit-box; margin: 0; overflow: hidden; font-size: 9px; line-height: 1.45; -webkit-line-clamp: 2; -webkit-box-orient: vertical; }
.search-result em { color: #43c9aa; font-style: normal; }

.sidebar-footer { flex: 0 0 auto; padding: 12px 16px 16px; border-top: 1px solid var(--sidebar-line); }
.source-lock { display: flex; align-items: center; gap: 10px; padding: 10px; color: #94aaa4; border: 1px solid rgba(255,255,255,.065); border-radius: 11px; background: rgba(0,0,0,.09); }
.source-lock svg { flex: 0 0 auto; width: 22px; color: #48c9ab; }
.source-lock strong, .source-lock small { display: block; }
.source-lock strong { color: #c7d7d3; font-size: 10px; }
.source-lock small { margin-top: 2px; color: #637b75; font-size: 8px; }

.icon-button, .text-button { display: inline-flex; align-items: center; justify-content: center; border: 0; cursor: pointer; }
.icon-button { width: 38px; height: 38px; flex: 0 0 auto; color: #5e6b68; background: transparent; border-radius: 11px; }
.icon-button:hover { color: var(--ink); background: rgba(24,36,35,.06); }
.text-button { height: 36px; gap: 7px; padding: 0 11px; color: #68736f; background: transparent; border-radius: 10px; font-size: 11px; font-weight: 650; }
.text-button:hover, .text-button.active { color: #273b37; background: #eef0eb; }
.text-button svg { width: 17px; }

.reader-main { min-width: 0; min-height: 0; display: flex; flex-direction: column; overflow: hidden; background: var(--canvas); }
.reader-toolbar {
  position: relative;
  z-index: 20;
  min-height: 66px;
  display: grid;
  grid-template-columns: minmax(150px,1fr) auto minmax(150px,1fr);
  align-items: center;
  gap: 14px;
  padding: 0 20px;
  background: rgba(255,254,250,.92);
  border-bottom: 1px solid var(--line);
  backdrop-filter: blur(16px);
}
.toolbar-start, .toolbar-end { display: flex; align-items: center; gap: 10px; }
.toolbar-end { justify-content: flex-end; }
.breadcrumb { min-width: 0; display: flex; align-items: center; gap: 8px; color: #8b9490; font-size: 10px; white-space: nowrap; }
.breadcrumb i { color: #c1c5c1; font-style: normal; }
.breadcrumb strong { overflow: hidden; color: #3c4845; font-weight: 650; text-overflow: ellipsis; }
.mode-switch { display: flex; padding: 3px; background: #ebece7; border-radius: 11px; }
.mode-switch button { height: 30px; min-width: 49px; padding: 0 10px; color: #717b77; background: transparent; border: 0; border-radius: 8px; cursor: pointer; font-size: 10px; font-weight: 700; }
.mode-switch button:hover { color: #2e3c38; }
.mode-switch button.active { color: #fff; background: #233b37; box-shadow: 0 3px 9px rgba(26,50,46,.2); }
.mode-switch button:disabled { opacity: .35; cursor: not-allowed; }
.reading-progress-track { position: absolute; right: 0; bottom: -1px; left: 0; height: 2px; overflow: hidden; }
.reading-progress-track span { display: block; width: 0; height: 100%; background: linear-gradient(90deg, var(--teal), var(--blue)); transition: width .12s linear; }

.reader-scroll { min-height: 0; flex: 1; overflow: auto; scroll-behavior: smooth; scrollbar-width: thin; scrollbar-color: #c8c8bf transparent; }
.lesson-stage { min-height: 100%; padding: 48px clamp(24px, 4vw, 72px) 80px; }
.loading-screen { min-height: calc(100dvh - 180px); display: grid; place-content: center; justify-items: center; color: #7d8783; }
.loading-screen p { margin-top: 20px; font-size: 12px; letter-spacing: .05em; }
.loading-orbit { position: relative; width: 66px; height: 66px; border: 1px solid #d1d6d1; border-radius: 50%; animation: rotate 4s linear infinite; }
.loading-orbit i { position: absolute; width: 10px; height: 10px; border-radius: 50%; background: var(--teal); }
.loading-orbit i:nth-child(1) { top: -5px; left: 28px; }
.loading-orbit i:nth-child(2) { right: 2px; bottom: 8px; background: var(--blue); }
.loading-orbit i:nth-child(3) { bottom: 5px; left: 3px; background: var(--coral); }
@keyframes rotate { to { transform: rotate(360deg); } }

.lesson-header { width: min(920px, 100%); margin: 0 auto 25px; }
.lesson-meta { display: flex; align-items: center; gap: 9px; margin-bottom: 13px; }
.lesson-index { padding: 5px 9px; color: #fff; background: var(--blue); border-radius: 6px; font-size: 9px; font-weight: 850; letter-spacing: .08em; }
.lesson-module { color: var(--teal); font-size: 10px; font-weight: 800; letter-spacing: .08em; }
.lesson-header h1 { max-width: 780px; margin: 0; font-family: "STSong", "Songti SC", Georgia, serif; font-size: clamp(32px, 4vw, 54px); font-weight: 800; line-height: 1.16; letter-spacing: -.035em; }
.lesson-header .english-title { margin: 11px 0 18px; color: #838b87; font-family: Georgia, serif; font-size: 14px; font-style: italic; }
.lesson-facts { display: flex; flex-wrap: wrap; gap: 8px; }
.fact-pill { display: inline-flex; align-items: center; gap: 6px; padding: 6px 9px; color: #5e6b67; background: rgba(255,255,255,.65); border: 1px solid #ddded7; border-radius: 20px; font-size: 9px; font-weight: 650; }
.fact-pill svg { width: 14px; height: 14px; }
.fact-pill.verified { color: #087d6c; border-color: #b8ddd4; background: #eefaf6; }
.fact-pill.attention { color: #a06e11; border-color: #ead5aa; background: #fff8e8; }

.reading-paper { width: min(920px, 100%); margin: 0 auto; padding: clamp(30px, 5vw, 68px); background: var(--paper); border: 1px solid rgba(203,203,194,.8); border-radius: 22px; box-shadow: var(--shadow); }
.reading-paper.bilingual-paper { width: min(1380px, 100%); }
.document-label { display: flex; align-items: center; gap: 9px; padding-bottom: 18px; margin-bottom: 28px; color: #7b8581; border-bottom: 1px solid #ecebe5; font-size: 9px; font-weight: 800; letter-spacing: .1em; text-transform: uppercase; }
.document-label i { width: 8px; height: 8px; border-radius: 50%; background: var(--teal); }
.document-label.original i { background: var(--blue); }
.bilingual-grid { display: grid; grid-template-columns: minmax(0, 1fr) minmax(0, 1fr); gap: 54px; }
.bilingual-column { min-width: 0; }
.bilingual-column + .bilingual-column { position: relative; }
.bilingual-column + .bilingual-column::before { content: ""; position: absolute; top: 0; bottom: 0; left: -27px; width: 1px; background: #e5e4dd; }

.prose { color: #27312f; font-family: ui-serif, "STSong", "Songti SC", Georgia, serif; font-size: 17px; line-height: 1.88; overflow-wrap: anywhere; }
.prose > :first-child { margin-top: 0; }
.prose h1, .prose h2, .prose h3 { scroll-margin-top: 95px; color: #172321; font-family: Inter, ui-sans-serif, -apple-system, "PingFang SC", sans-serif; letter-spacing: -.02em; }
.prose h1 { margin: 0 0 34px; padding-bottom: 18px; border-bottom: 1px solid #e8e7e0; font-family: "STSong", "Songti SC", Georgia, serif; font-size: 34px; line-height: 1.25; }
.prose h2 { margin: 57px 0 19px; font-size: 25px; line-height: 1.35; }
.prose h2::before { content: ""; display: inline-block; width: 5px; height: .85em; margin-right: 11px; border-radius: 3px; background: linear-gradient(var(--teal), #5bd9bf); transform: translateY(1px); }
.prose h3 { margin: 34px 0 14px; font-size: 19px; line-height: 1.45; }
.prose p { margin: 0 0 19px; }
.prose strong { color: #111c1a; font-weight: 750; }
.prose em { color: #4d5c58; }
.prose a { color: #3153d4; text-decoration: underline; text-decoration-color: #bdc8f8; text-decoration-thickness: 1px; text-underline-offset: 3px; }
.prose a:hover { color: #173bbf; text-decoration-color: #3153d4; }
.prose ul, .prose ol { padding-left: 1.45em; margin: 13px 0 24px; }
.prose li { padding-left: .25em; margin: 7px 0; }
.prose li::marker { color: var(--teal); font-weight: 800; }
.prose hr { height: 1px; margin: 42px 0; background: linear-gradient(90deg, transparent, #d7d7ce, transparent); border: 0; }
.prose blockquote { position: relative; margin: 26px 0; padding: 17px 20px 17px 22px; color: #4c5a56; background: #f3f5f1; border-left: 4px solid #9bb5ad; border-radius: 0 12px 12px 0; }
.prose blockquote > :last-child { margin-bottom: 0; }
.prose .callout { padding: 19px 21px; border: 1px solid #d7e5e0; border-left: 4px solid var(--teal); border-radius: 12px; background: #f1faf7; }
.prose .callout-label { margin-bottom: 8px; color: #087d6c; font-family: Inter, sans-serif; font-size: 11px; font-weight: 850; letter-spacing: .04em; }
.prose .callout-warning { border-color: #ecd9ae; border-left-color: var(--gold); background: #fff9ea; }
.prose .callout-warning .callout-label { color: #a06d0e; }
.prose .callout-question { border-color: #ccd4f6; border-left-color: var(--blue); background: #f3f5ff; }
.prose .callout-question .callout-label { color: var(--blue); }
.prose .callout-example { border-color: #efd3ca; border-left-color: var(--coral); background: #fff5f1; }
.prose .callout-example .callout-label { color: #bb4934; }
.prose code { padding: .16em .38em; color: #a03f42; background: #f6eeee; border-radius: 5px; font-family: "SFMono-Regular", Consolas, monospace; font-size: .85em; }
.prose pre { position: relative; max-width: 100%; margin: 25px 0; padding: 21px; overflow: auto; color: #d9e5e1; background: #172321; border: 1px solid #263c37; border-radius: 13px; box-shadow: 0 12px 26px rgba(18,36,32,.13); }
.prose pre code { padding: 0; color: inherit; background: transparent; font-size: 12px; line-height: 1.7; }
.prose table { width: 100%; display: table; margin: 27px 0; overflow: hidden; border-collapse: separate; border-spacing: 0; border: 1px solid #dcded8; border-radius: 11px; font-family: Inter, sans-serif; font-size: 12px; line-height: 1.55; }
.prose th, .prose td { padding: 11px 13px; vertical-align: top; border-right: 1px solid #e0e1dc; border-bottom: 1px solid #e0e1dc; }
.prose th:last-child, .prose td:last-child { border-right: 0; }
.prose tr:last-child td { border-bottom: 0; }
.prose th { color: #2d4640; background: #eef2ef; font-weight: 750; text-align: left; }
.prose tr:nth-child(even) td { background: #fbfbf8; }
.prose img { max-width: 100%; height: auto; display: block; margin: 28px auto 11px; border-radius: 12px; background: #f0f0eb; box-shadow: 0 10px 30px rgba(25,38,35,.1); cursor: zoom-in; transition: transform .2s ease, box-shadow .2s ease; }
.prose img:hover { transform: translateY(-2px); box-shadow: 0 16px 38px rgba(25,38,35,.16); }
.prose img.image-error { min-height: 120px; opacity: .35; border: 1px dashed #c66; }
.prose [data-block-id] { position: relative; }
.explain-marker { width: 23px; height: 23px; display: inline-grid; place-items: center; margin-left: 7px; color: #fff; background: linear-gradient(145deg, var(--coral), #d94340); border: 2px solid #fff; border-radius: 50%; box-shadow: 0 2px 0 #c53f32, 0 0 0 3px rgba(240,100,73,.12); cursor: pointer; font-family: Inter, sans-serif; font-size: 11px; font-weight: 900; line-height: 1; vertical-align: .1em; animation: marker-in .35s ease both; }
.explain-marker:hover { transform: scale(1.12); box-shadow: 0 2px 0 #c53f32, 0 0 0 6px rgba(240,100,73,.14); }
@keyframes marker-in { from { opacity: 0; transform: scale(.4) rotate(-20deg); } }
.bilingual-grid .prose { font-size: 15px; line-height: 1.78; }
.bilingual-grid .prose h1 { font-size: 27px; }
.bilingual-grid .prose h2 { font-size: 20px; }
.bilingual-grid .prose table { display: block; overflow-x: auto; }

.lesson-footer { width: min(920px, 100%); display: grid; grid-template-columns: 1fr auto 1fr; align-items: center; gap: 14px; margin: 23px auto 0; }
.lesson-nav-button { min-height: 56px; display: flex; align-items: center; gap: 10px; padding: 9px 15px; color: #52605c; background: rgba(255,255,255,.62); border: 1px solid #dadbd4; border-radius: 13px; cursor: pointer; text-align: left; }
.lesson-nav-button.next { justify-content: flex-end; text-align: right; }
.lesson-nav-button:hover { color: #193a34; border-color: #aebdb8; background: #fff; }
.lesson-nav-button svg { width: 17px; }
.lesson-nav-button.previous svg { transform: rotate(180deg); }
.lesson-nav-button small, .lesson-nav-button strong { display: block; }
.lesson-nav-button small { color: #919994; font-size: 8px; letter-spacing: .08em; text-transform: uppercase; }
.lesson-nav-button strong { max-width: 180px; margin-top: 3px; overflow: hidden; font-size: 11px; text-overflow: ellipsis; white-space: nowrap; }
.lesson-nav-button:disabled { visibility: hidden; }
.lesson-position { color: #89928e; font-size: 9px; font-weight: 700; letter-spacing: .08em; }
.error-state { width: min(680px, 100%); margin: 70px auto; padding: 35px; background: white; border: 1px solid #e5c8c2; border-radius: 18px; text-align: center; }
.error-state strong { display: block; color: #a84534; font-size: 18px; }
.error-state p { color: #7a706d; }

.inspector {
  position: relative;
  z-index: 25;
  min-width: 0;
  display: flex;
  flex-direction: column;
  overflow: hidden;
  background: #fffefa;
  border-left: 1px solid var(--line);
  box-shadow: -16px 0 34px rgba(28,44,40,.025);
  transition: opacity 180ms ease, transform 240ms cubic-bezier(.22,.7,.23,1);
}
.inspector-collapsed .inspector { opacity: 0; pointer-events: none; transform: translateX(24px); }
.inspector-header { min-height: 92px; display: flex; align-items: flex-start; justify-content: space-between; padding: 22px 19px 16px 23px; border-bottom: 1px solid #e6e5de; }
.eyebrow { display: flex; align-items: center; gap: 6px; color: var(--coral); font-size: 8px; font-weight: 850; letter-spacing: .12em; }
.eyebrow svg { width: 13px; height: 13px; }
.inspector-header h2 { margin: 6px 0 0; font-family: "STSong", "Songti SC", serif; font-size: 24px; }
.inspector-content { min-height: 0; flex: 1; padding: 20px 20px 28px; overflow-y: auto; scrollbar-width: thin; scrollbar-color: #d5d5ce transparent; }
.inspector-empty { min-height: 320px; display: flex; flex-direction: column; align-items: center; justify-content: center; padding: 25px; text-align: center; }
.empty-orbit { width: 82px; height: 82px; display: grid; place-items: center; border: 1px dashed #d2c9be; border-radius: 50%; background: radial-gradient(circle, #fff 35%, #f6f1e9); }
.empty-orbit span { width: 35px; height: 35px; display: grid; place-items: center; color: #fff; background: var(--coral); border-radius: 50%; box-shadow: 0 8px 22px rgba(240,100,73,.25); font-weight: 900; }
.inspector-empty h3 { margin: 21px 0 8px; font-size: 16px; }
.inspector-empty p { max-width: 270px; margin: 0; color: #7a8581; font-size: 11px; line-height: 1.7; }
.explanation-index-head { margin-bottom: 17px; }
.explanation-index-head strong { display: block; font-size: 14px; }
.explanation-index-head p { margin: 6px 0 0; color: #7d8783; font-size: 10px; line-height: 1.55; }
.explanation-list { display: grid; gap: 9px; }
.explanation-list-item { width: 100%; display: grid; grid-template-columns: 34px minmax(0,1fr) 16px; align-items: center; gap: 9px; padding: 11px; color: #33403d; background: #f7f6f1; border: 1px solid #e5e3db; border-radius: 12px; cursor: pointer; text-align: left; transition: transform .15s, border-color .15s, background .15s; }
.explanation-list-item:hover { transform: translateX(3px); background: #fff; border-color: #c6cec9; }
.explanation-list-item .kind-icon { width: 32px; height: 32px; display: grid; place-items: center; color: #b84935; background: #fdebe6; border-radius: 9px; font-size: 9px; font-weight: 850; }
.explanation-list-item strong { display: block; font-size: 11px; line-height: 1.4; }
.explanation-list-item small { display: block; margin-top: 3px; overflow: hidden; color: #8b9490; font-size: 9px; text-overflow: ellipsis; white-space: nowrap; }
.explanation-list-item svg { width: 14px; color: #a1aaa6; }
.explanation-detail { animation: detail-in .25s ease both; }
@keyframes detail-in { from { opacity: 0; transform: translateY(8px); } }
.detail-back { display: inline-flex; align-items: center; gap: 5px; padding: 0; margin-bottom: 15px; color: #75807c; background: none; border: 0; cursor: pointer; font-size: 9px; font-weight: 700; }
.detail-back svg { width: 14px; transform: rotate(180deg); }
.detail-kind { display: inline-flex; padding: 4px 7px; color: #b64330; background: #fdebe6; border-radius: 6px; font-size: 8px; font-weight: 850; letter-spacing: .05em; }
.explanation-detail h3 { margin: 10px 0 17px; font-family: "STSong", "Songti SC", serif; font-size: 24px; line-height: 1.32; }
.detail-lead { padding: 16px; margin-bottom: 12px; color: #24423b; background: linear-gradient(140deg, #eaf8f4, #f4fbf9); border: 1px solid #cce6df; border-radius: 13px; font-size: 12px; font-weight: 650; line-height: 1.65; }
.detail-card { margin: 11px 0; padding: 15px; border: 1px solid #e1e2dc; border-radius: 12px; background: #fff; }
.detail-card h4 { display: flex; align-items: center; gap: 7px; margin: 0 0 8px; color: #596661; font-size: 9px; font-weight: 850; letter-spacing: .08em; text-transform: uppercase; }
.detail-card h4::before { content: ""; width: 7px; height: 7px; border-radius: 50%; background: var(--teal); }
.detail-card.example h4::before { background: var(--blue); }
.detail-card.warning h4::before { background: var(--gold); }
.detail-card p { margin: 0; color: #46534f; font-size: 11px; line-height: 1.72; }
.related-tags { display: flex; flex-wrap: wrap; gap: 6px; margin-top: 14px; }
.related-tags span { padding: 5px 8px; color: #687571; background: #f0f1ed; border-radius: 12px; font-size: 8px; }

.ai-dock { flex: 0 0 auto; padding: 15px 18px 18px; background: #f3f2ec; border-top: 1px solid #ddddd5; }
.ai-dock-head { display: flex; align-items: center; justify-content: space-between; margin-bottom: 9px; }
.ai-dock-head > span { display: flex; align-items: center; gap: 6px; color: #4b5753; font-size: 10px; font-weight: 800; }
.ai-dock-head svg { width: 14px; color: var(--blue); }
.ai-dock-head em { padding: 3px 6px; color: #8c7161; background: #eee4db; border-radius: 5px; font-size: 7px; font-style: normal; font-weight: 750; }
.ai-input-wrap { display: flex; gap: 7px; padding: 8px 8px 8px 11px; background: #fff; border: 1px solid #d9dad4; border-radius: 12px; }
.ai-input-wrap:focus-within { border-color: #9aa9e8; box-shadow: 0 0 0 3px rgba(56,88,233,.08); }
.ai-input-wrap textarea { min-width: 0; flex: 1; resize: none; color: #43504c; background: transparent; border: 0; outline: 0; font-size: 10px; line-height: 1.5; }
.ai-input-wrap textarea::placeholder { color: #a5aaa7; }
.ai-input-wrap button { width: 32px; height: 32px; align-self: flex-end; display: grid; place-items: center; color: #fff; background: #263f3a; border: 0; border-radius: 9px; cursor: pointer; }
.ai-input-wrap button:hover { background: var(--blue); }
.ai-input-wrap button svg { width: 15px; }
.ai-dock > small { display: block; margin: 7px 2px 0; color: #939a96; font-size: 8px; line-height: 1.4; }

.image-lightbox { max-width: none; max-height: none; width: 100vw; height: 100dvh; padding: 35px; margin: 0; background: rgba(10,17,16,.94); border: 0; }
.image-lightbox[open] { display: grid; place-items: center; grid-template-rows: minmax(0,1fr) auto; }
.image-lightbox::backdrop { background: rgba(10,17,16,.5); backdrop-filter: blur(8px); }
.image-lightbox img { max-width: min(1400px, 92vw); max-height: 84dvh; object-fit: contain; border-radius: 8px; box-shadow: 0 25px 80px rgba(0,0,0,.4); }
.image-lightbox p { max-width: 800px; margin: 13px 0 0; color: #d4dedb; font-size: 11px; text-align: center; }
.lightbox-close { position: absolute; top: 20px; right: 22px; width: 42px; height: 42px; display: grid; place-items: center; color: #e8f0ed; background: rgba(255,255,255,.1); border: 1px solid rgba(255,255,255,.15); border-radius: 50%; cursor: pointer; }
.lightbox-close svg { width: 20px; }
.toast { position: fixed; z-index: 100; right: 24px; bottom: 24px; max-width: 360px; padding: 12px 16px; color: #e9f4f0; background: #1b302c; border: 1px solid #35504a; border-radius: 11px; box-shadow: 0 14px 40px rgba(13,28,25,.25); font-size: 11px; line-height: 1.5; opacity: 0; pointer-events: none; transform: translateY(12px); transition: opacity .2s, transform .2s; }
.toast.show { opacity: 1; transform: translateY(0); }
.mobile-overlay { position: fixed; z-index: 28; inset: 0; background: rgba(8,16,15,.48); backdrop-filter: blur(2px); }

@media (max-width: 1320px) {
  :root { --sidebar-width: 292px; --inspector-width: 350px; }
  .lesson-stage { padding-right: 32px; padding-left: 32px; }
  .reading-paper { padding: 44px; }
  .prose { font-size: 16px; }
}

@media (max-width: 1120px) {
  .app-shell, .app-shell.inspector-collapsed { grid-template-columns: var(--sidebar-width) minmax(0,1fr); }
  .app-shell.nav-collapsed, .app-shell.nav-collapsed.inspector-collapsed { grid-template-columns: 0 minmax(0,1fr); }
  .inspector { position: fixed; z-index: 45; top: 0; right: 0; bottom: 0; width: min(var(--inspector-width), 92vw); box-shadow: -25px 0 60px rgba(16,29,27,.18); }
  .inspector-collapsed .inspector { transform: translateX(100%); }
}

@media (max-width: 820px) {
  :root { --sidebar-width: min(340px, 90vw); }
  .app-shell, .app-shell.nav-collapsed, .app-shell.inspector-collapsed, .app-shell.nav-collapsed.inspector-collapsed { display: block; }
  .sidebar { position: fixed; z-index: 50; top: 0; bottom: 0; left: 0; width: var(--sidebar-width); box-shadow: 25px 0 60px rgba(9,20,18,.24); }
  .nav-collapsed .sidebar { transform: translateX(-100%); }
  .reader-main { height: 100dvh; }
  .reader-toolbar { grid-template-columns: 1fr auto; min-height: 62px; padding: 0 12px; }
  .toolbar-start { min-width: 0; }
  .breadcrumb span, .breadcrumb i { display: none; }
  .toolbar-end { display: none; }
  .mode-switch { grid-column: 2; grid-row: 1; }
  .mode-switch button { min-width: 40px; padding: 0 7px; }
  .lesson-stage { padding: 27px 13px 55px; }
  .lesson-header { padding: 0 7px; }
  .lesson-header h1 { font-size: 34px; }
  .reading-paper { padding: 27px 22px; border-radius: 16px; }
  .bilingual-grid { grid-template-columns: 1fr; gap: 55px; }
  .bilingual-column + .bilingual-column::before { top: -28px; right: 0; bottom: auto; left: 0; width: auto; height: 1px; }
  .prose { font-size: 16px; line-height: 1.82; }
  .prose h1 { font-size: 28px; }
  .prose h2 { margin-top: 45px; font-size: 22px; }
  .prose table { display: block; overflow-x: auto; white-space: normal; }
  .lesson-footer { grid-template-columns: 1fr 1fr; }
  .lesson-position { display: none; }
  .inspector { width: min(390px, 94vw); }
}

@media (max-width: 520px) {
  .breadcrumb { display: none; }
  .reader-toolbar { grid-template-columns: auto 1fr; }
  .mode-switch { justify-self: end; }
  .mode-switch button { min-width: 43px; }
  .lesson-header h1 { font-size: 29px; }
  .lesson-facts { gap: 5px; }
  .fact-pill { padding: 5px 7px; }
  .reading-paper { padding: 23px 17px; }
  .prose { font-size: 15.5px; }
  .prose h1 { font-size: 25px; }
  .prose h2 { font-size: 21px; }
  .prose table { font-size: 11px; }
  .prose th, .prose td { min-width: 135px; padding: 9px 10px; }
  .lesson-nav-button strong { max-width: 110px; }
}

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { scroll-behavior: auto !important; animation-duration: .01ms !important; animation-iteration-count: 1 !important; transition-duration: .01ms !important; }
}

/* Practice and static Notebook view --------------------------------------- */
.lesson-view-switch {
  display: inline-flex;
  align-items: center;
  gap: 3px;
  max-width: 100%;
  padding: 3px;
  overflow-x: auto;
  background: #e9ebe6;
  border: 1px solid #dde0da;
  border-radius: 12px;
  scrollbar-width: none;
}
.lesson-view-switch::-webkit-scrollbar { display: none; }
.view-switch-button {
  min-width: 74px;
  min-height: 34px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 7px;
  flex: 0 0 auto;
  padding: 0 13px;
  color: #6b7672;
  background: transparent;
  border: 0;
  border-radius: 9px;
  cursor: pointer;
  font-size: 11px;
  font-weight: 750;
  transition: color .18s ease, background .18s ease, box-shadow .18s ease, transform .18s ease;
}
.view-switch-button:hover { color: #1c3530; background: rgba(255,255,255,.62); }
.view-switch-button.active,
.view-switch-button[aria-selected="true"] {
  color: #fff;
  background: #203b35;
  box-shadow: 0 4px 12px rgba(24,53,46,.18);
}
.view-switch-button:active { transform: translateY(1px); }

.practice-hero,
.practice-story,
.artifact-switch,
.notebook-shell,
.inline-guide,
.practice-checklist,
.practice-footer-actions {
  width: min(1120px, 100%);
  margin-right: auto;
  margin-left: auto;
}

.practice-hero {
  position: relative;
  isolation: isolate;
  min-height: 330px;
  padding: clamp(36px, 6vw, 72px);
  overflow: hidden;
  color: #eff8f5;
  background:
    radial-gradient(circle at 86% 15%, rgba(119,235,202,.2), transparent 27%),
    radial-gradient(circle at 12% 100%, rgba(56,88,233,.19), transparent 35%),
    linear-gradient(142deg, #10241f 0%, #193c33 57%, #17302b 100%);
  border: 1px solid rgba(10,29,24,.72);
  border-radius: 26px;
  box-shadow: 0 28px 70px rgba(24,49,43,.17);
}
.practice-hero::before {
  content: "";
  position: absolute;
  z-index: -1;
  top: -88px;
  right: -45px;
  width: 330px;
  height: 330px;
  border: 1px solid rgba(164,240,218,.12);
  border-radius: 50%;
  box-shadow: 0 0 0 54px rgba(164,240,218,.035), 0 0 0 108px rgba(164,240,218,.022);
}
.practice-kicker {
  display: inline-flex;
  align-items: center;
  gap: 9px;
  margin: 0 0 24px;
  color: #8ee5cc;
  font-size: 10px;
  font-weight: 850;
  letter-spacing: .14em;
  text-transform: uppercase;
}
.practice-kicker::before { content: ""; width: 26px; height: 1px; background: currentColor; }
.practice-hero h1 {
  max-width: 760px;
  margin: 0;
  font-family: "STSong", "Songti SC", Georgia, serif;
  font-size: clamp(40px, 5.1vw, 68px);
  font-weight: 800;
  line-height: 1.08;
  letter-spacing: -.045em;
}
.practice-hero > p {
  max-width: 720px;
  margin: 22px 0 0;
  color: #b8ccc6;
  font-size: 15px;
  line-height: 1.8;
}
.practice-facts { display: flex; flex-wrap: wrap; gap: 8px; margin-top: 32px; }
.practice-facts > * {
  display: inline-flex;
  align-items: center;
  gap: 7px;
  min-height: 30px;
  padding: 6px 11px;
  color: #d3e6e0;
  background: rgba(255,255,255,.075);
  border: 1px solid rgba(208,239,230,.13);
  border-radius: 999px;
  font-size: 10px;
  font-weight: 700;
  backdrop-filter: blur(8px);
}

.practice-story {
  position: relative;
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 14px;
  margin-top: 24px;
}
.practice-story::before {
  content: "";
  position: absolute;
  top: 37px;
  right: 11%;
  left: 11%;
  height: 1px;
  background: linear-gradient(90deg, transparent, #bdc9c4 13%, #bdc9c4 87%, transparent);
}
.story-step {
  position: relative;
  min-width: 0;
  min-height: 165px;
  padding: 27px 25px 24px;
  color: #33423e;
  background: rgba(255,255,255,.76);
  border: 1px solid #dcddd6;
  border-radius: 18px;
  box-shadow: 0 12px 35px rgba(30,48,43,.055);
}
.story-step > span:first-child,
.story-step > small:first-child {
  position: relative;
  z-index: 1;
  width: 22px;
  height: 22px;
  display: grid;
  place-items: center;
  margin-bottom: 22px;
  color: #fff;
  background: #1a8c77;
  border: 4px solid #f7f6f1;
  border-radius: 50%;
  box-shadow: 0 0 0 1px #77b9aa;
  font-size: 8px;
  font-weight: 850;
}
.story-step h2,
.story-step h3 { margin: 0 0 9px; color: #192925; font-size: 17px; line-height: 1.35; }
.story-step p { margin: 0; color: #6d7975; font-size: 12px; line-height: 1.72; }

.artifact-switch {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(230px, 1fr));
  gap: 11px;
  margin-top: 34px;
  margin-bottom: 14px;
}
.artifact-card {
  position: relative;
  min-width: 0;
  min-height: 104px;
  display: flex;
  flex-direction: column;
  align-items: flex-start;
  justify-content: center;
  gap: 7px;
  padding: 17px 45px 17px 18px;
  color: #58645f;
  background: rgba(255,255,255,.68);
  border: 1px solid #d9dad3;
  border-radius: 15px;
  cursor: pointer;
  text-align: left;
  transition: color .18s ease, border-color .18s ease, background .18s ease, box-shadow .18s ease, transform .18s ease;
}
.artifact-card::after {
  content: "↗";
  position: absolute;
  top: 15px;
  right: 16px;
  color: #a8b0ac;
  font-size: 14px;
}
.artifact-card:hover { transform: translateY(-2px); color: #273a35; background: #fff; border-color: #b9c8c2; }
.artifact-card.active,
.artifact-card[aria-selected="true"] {
  color: #213d36;
  background: #eef8f4;
  border-color: #7dc6b4;
  box-shadow: 0 10px 30px rgba(23,110,91,.11);
}
.artifact-card.active::after,
.artifact-card[aria-selected="true"]::after { content: "✓"; color: #0e947c; font-weight: 900; }
.artifact-card strong { color: #1f312c; font-size: 14px; line-height: 1.35; }
.artifact-role {
  color: #168d77;
  font-size: 9px;
  font-weight: 850;
  letter-spacing: .1em;
  text-transform: uppercase;
}
.artifact-meta { max-width: 100%; overflow: hidden; color: #8a9490; font-size: 10px; line-height: 1.45; text-overflow: ellipsis; white-space: nowrap; }

.notebook-shell {
  margin-top: 14px;
  overflow: hidden;
  color: #2b3834;
  background: #f7f7f3;
  border: 1px solid #d4d6cf;
  border-radius: 23px;
  box-shadow: 0 24px 65px rgba(25,39,35,.1);
}
.notebook-head {
  min-height: 82px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 18px;
  padding: 17px 22px;
  color: #e5efec;
  background: linear-gradient(105deg, #1b302b, #243e38);
  border-bottom: 1px solid #142621;
}
.notebook-head > div { min-width: 0; }
.notebook-head h2,
.notebook-head h3 { margin: 0; overflow: hidden; font-size: 15px; line-height: 1.4; text-overflow: ellipsis; white-space: nowrap; }
.notebook-head p,
.notebook-head small { display: block; margin: 5px 0 0; color: #8fa8a1; font-size: 9px; line-height: 1.45; }
.notebook-head > span,
.notebook-head > em {
  flex: 0 0 auto;
  padding: 5px 8px;
  color: #a9e8d7;
  background: rgba(69,189,158,.12);
  border: 1px solid rgba(130,223,199,.18);
  border-radius: 8px;
  font-size: 8px;
  font-style: normal;
  font-weight: 800;
  letter-spacing: .08em;
}
.notebook-notice {
  display: flex;
  align-items: flex-start;
  gap: 11px;
  padding: 13px 20px;
  color: #6c6044;
  background: #fff8e7;
  border-bottom: 1px solid #eadcb9;
  font-size: 11px;
  line-height: 1.65;
}
.notebook-notice::before { content: "i"; width: 19px; height: 19px; display: grid; place-items: center; flex: 0 0 auto; margin-top: 1px; color: #fff; background: #c08c24; border-radius: 50%; font-family: Georgia, serif; font-size: 11px; font-weight: 800; }

.notebook-cell {
  min-width: 0;
  margin: 16px;
  overflow: hidden;
  background: #fff;
  border: 1px solid #dbddd6;
  border-radius: 14px;
  box-shadow: 0 5px 18px rgba(25,38,34,.035);
}
.notebook-cell + .notebook-cell { margin-top: 0; }
.notebook-cell.markdown-cell { padding: clamp(22px, 3.5vw, 39px); }
.markdown-cell { color: #33403d; font-family: ui-serif, "STSong", "Songti SC", Georgia, serif; font-size: 15px; line-height: 1.8; }
.markdown-cell > :first-child { margin-top: 0; }
.markdown-cell > :last-child { margin-bottom: 0; }
.markdown-cell h1,
.markdown-cell h2,
.markdown-cell h3 { color: #172522; font-family: Inter, ui-sans-serif, "PingFang SC", sans-serif; line-height: 1.35; }
.markdown-cell h1 { font-size: 26px; }
.markdown-cell h2 { margin-top: 29px; font-size: 21px; }
.markdown-cell h3 { margin-top: 23px; font-size: 17px; }
.markdown-cell p { margin: 0 0 15px; }
.markdown-cell a { color: #3153d4; text-underline-offset: 3px; }
.markdown-cell ul,
.markdown-cell ol { padding-left: 1.35em; }
.markdown-cell code { padding: .14em .36em; color: #9f4044; background: #f6eeee; border-radius: 5px; font-family: "SFMono-Regular", Consolas, monospace; font-size: .86em; }
.markdown-cell img,
.notebook-output.output-image img,
.output-image img {
  max-width: 100%;
  height: auto;
  display: block;
  margin: 20px auto 8px;
  border: 1px solid #e0e1db;
  border-radius: 11px;
  box-shadow: 0 10px 28px rgba(26,39,35,.09);
  cursor: zoom-in;
  transition: transform .2s ease, box-shadow .2s ease;
}
.markdown-cell img:hover,
.notebook-output.output-image img:hover,
.output-image img:hover { transform: translateY(-2px); box-shadow: 0 16px 38px rgba(26,39,35,.14); }

.cell-toolbar {
  min-height: 44px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  padding: 6px 9px 6px 14px;
  color: #78827e;
  background: #f1f2ed;
  border-bottom: 1px solid #d9dbd4;
}
.cell-index { font-family: "SFMono-Regular", Consolas, monospace; font-size: 9px; font-weight: 800; letter-spacing: .06em; }
.cell-actions { display: flex; align-items: center; gap: 5px; }
.cell-actions button,
.copy-code {
  min-width: 34px;
  min-height: 32px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 6px;
  padding: 0 9px;
  color: #5e6b67;
  background: rgba(255,255,255,.78);
  border: 1px solid #d6d9d2;
  border-radius: 8px;
  cursor: pointer;
  font-size: 9px;
  font-weight: 750;
}
.cell-actions button:hover,
.copy-code:hover { color: #fff; background: #29443d; border-color: #29443d; }

.cell-source {
  max-width: 100%;
  overflow-x: auto;
  color: #dbe7e3;
  background: #15231f;
  scrollbar-width: thin;
  scrollbar-color: #49615a #15231f;
}
.code-lines { min-width: max-content; padding: 17px 0; font-family: "SFMono-Regular", Consolas, "Liberation Mono", monospace; font-size: 12px; line-height: 1.72; }
.code-line { min-height: 21px; display: grid; grid-template-columns: 50px minmax(max-content, 1fr); }
.code-line:hover { background: rgba(255,255,255,.035); }
.line-number { position: sticky; left: 0; padding: 0 13px 0 8px; color: #60736d; background: #15231f; border-right: 1px solid #263833; text-align: right; user-select: none; }
.line-code { padding: 0 20px 0 14px; white-space: pre; tab-size: 4; }

.cell-outputs { display: grid; gap: 10px; padding: 13px; background: #f5f6f2; border-top: 1px solid #d8dad3; }
.notebook-output {
  min-width: 0;
  padding: 14px 16px;
  overflow: auto;
  color: #37443f;
  background: #fff;
  border: 1px solid #dfe1da;
  border-radius: 10px;
  font-family: "SFMono-Regular", Consolas, monospace;
  font-size: 11px;
  line-height: 1.65;
}
.notebook-output.output-image { padding: 10px; background: #fcfcfa; text-align: center; }
.notebook-output.output-image img,
.output-image img { margin: 0 auto; }
.notebook-output.output-text,
.output-text { white-space: pre-wrap; overflow-wrap: anywhere; }
.notebook-output.output-widget,
.output-widget { color: #315148; background: #edf8f4; border-color: #c7e6dc; font-family: Inter, sans-serif; }
.notebook-output.output-error,
.output-error { color: #8f3838; background: #fff2f1; border-color: #efc8c5; white-space: pre-wrap; }
.output-label {
  display: block;
  margin: 0 0 8px;
  color: #87918d;
  font-family: Inter, sans-serif;
  font-size: 8px;
  font-weight: 850;
  letter-spacing: .1em;
  text-transform: uppercase;
}

.inline-guide {
  display: grid;
  grid-template-columns: minmax(0, 1fr) auto;
  align-items: center;
  gap: 22px;
  margin-top: 20px;
  padding: 22px 23px 22px 26px;
  color: #29423b;
  background: linear-gradient(135deg, #eaf7f3, #f4faf7);
  border: 1px solid #cce2da;
  border-left: 5px solid #18a086;
  border-radius: 16px;
}
.guide-eyebrow { display: block; margin-bottom: 7px; color: #148b75; font-size: 9px; font-weight: 850; letter-spacing: .1em; text-transform: uppercase; }
.guide-body { min-width: 0; font-size: 12px; line-height: 1.72; }
.guide-body h3 { margin: 0 0 7px; color: #1c332d; font-size: 16px; }
.guide-body p { margin: 0; color: #60716b; }
.guide-action {
  min-height: 40px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 0 14px;
  color: #fff;
  background: #247d6b;
  border: 0;
  border-radius: 10px;
  cursor: pointer;
  font-size: 10px;
  font-weight: 800;
  white-space: nowrap;
}
.guide-action:hover { background: #156e5d; }

.practice-checklist {
  margin-top: 22px;
  padding: clamp(23px, 3vw, 34px);
  background: rgba(255,255,255,.78);
  border: 1px solid #d9dcd5;
  border-radius: 18px;
}
.practice-checklist h2,
.practice-checklist h3 { margin: 0 0 17px; color: #1e302b; font-size: 18px; }
.practice-checklist ul { display: grid; gap: 9px; padding: 0; margin: 0; list-style: none; }
.practice-checklist li,
.practice-checklist label { min-height: 42px; display: flex; align-items: flex-start; gap: 11px; color: #53615d; font-size: 12px; line-height: 1.65; }
.practice-checklist li::before { content: ""; width: 18px; height: 18px; flex: 0 0 auto; margin-top: 3px; border: 2px solid #9eb0aa; border-radius: 6px; background: #fff; }
.practice-checklist input[type="checkbox"] { width: 18px; height: 18px; flex: 0 0 auto; margin: 3px 0 0; accent-color: #168f78; }
.practice-checklist label:has(input) + li::before,
.practice-checklist li:has(input)::before { display: none; }

.practice-footer-actions {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 15px;
  margin-top: 22px;
  margin-bottom: 10px;
}
.download-button {
  min-height: 44px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 9px;
  padding: 0 17px;
  color: #fff;
  background: #203b35;
  border: 1px solid #203b35;
  border-radius: 11px;
  box-shadow: 0 8px 22px rgba(26,57,49,.14);
  cursor: pointer;
  font-size: 11px;
  font-weight: 800;
  text-decoration: none;
}
.download-button:hover { background: #315b50; border-color: #315b50; transform: translateY(-1px); }
.practice-footer-actions > a:not(.download-button),
.practice-footer-actions > button:not(.download-button) { color: #5d6b67; font-size: 11px; }

.lesson-view-tree { margin: 4px 7px 9px 38px; padding: 4px 0 4px 10px; border-left: 1px solid #34504a; }
.tree-view-link,
.tree-artifact-link {
  position: relative;
  width: 100%;
  min-height: 38px;
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 7px 9px;
  overflow: hidden;
  color: #7f9791;
  background: transparent;
  border: 0;
  border-radius: 8px;
  cursor: pointer;
  font-size: 11px;
  font-weight: 650;
  line-height: 1.4;
  text-align: left;
  text-decoration: none;
  text-overflow: ellipsis;
  white-space: nowrap;
}
.tree-view-link::before,
.tree-artifact-link::before { content: ""; width: 6px; height: 6px; flex: 0 0 auto; border: 1px solid #5c7770; border-radius: 50%; }
.tree-artifact-link::before { border-radius: 2px; transform: rotate(45deg); }
.tree-view-link:hover,
.tree-artifact-link:hover { color: #dceae6; background: rgba(255,255,255,.045); }
.tree-view-link.active,
.tree-artifact-link.active,
.tree-view-link[aria-current="page"],
.tree-artifact-link[aria-current="page"] { color: #b5f3e3; background: rgba(54,190,157,.12); }
.tree-view-link.active::before,
.tree-artifact-link.active::before,
.tree-view-link[aria-current="page"]::before,
.tree-artifact-link[aria-current="page"]::before { background: #52d3b3; border-color: #52d3b3; box-shadow: 0 0 0 3px rgba(82,211,179,.1); }

@media (max-width: 820px) {
  .lesson-view-switch { max-width: min(100%, 220px); }
  .view-switch-button { min-width: 68px; min-height: 44px; padding: 0 11px; }

  .practice-hero { min-height: 0; padding: 34px 24px; border-radius: 19px; }
  .practice-hero::before { top: -130px; right: -130px; }
  .practice-hero h1 { font-size: clamp(35px, 9vw, 48px); }
  .practice-hero > p { font-size: 14px; line-height: 1.75; }
  .practice-facts > * { min-height: 34px; }

  .practice-story { grid-template-columns: 1fr; gap: 10px; }
  .practice-story::before { display: none; }
  .story-step { min-height: 0; padding: 22px; }
  .story-step > span:first-child,
  .story-step > small:first-child { margin-bottom: 15px; }

  .artifact-switch { grid-template-columns: 1fr; margin-top: 25px; }
  .artifact-card { min-height: 96px; }
  .notebook-shell { border-radius: 17px; }
  .notebook-head { min-height: 76px; flex-wrap: wrap; padding: 15px 17px; }
  .notebook-notice { padding: 13px 15px; }
  .notebook-cell { margin: 10px; border-radius: 11px; }
  .notebook-cell + .notebook-cell { margin-top: 0; }
  .notebook-cell.markdown-cell { padding: 23px 19px; }
  .markdown-cell { font-size: 14.5px; }

  .cell-toolbar { min-height: 52px; padding-left: 12px; }
  .cell-actions button,
  .copy-code { min-width: 44px; min-height: 44px; }
  .code-lines { font-size: 11.5px; }
  .code-line { grid-template-columns: 43px minmax(max-content, 1fr); }
  .line-number { padding-right: 10px; }
  .line-code { padding-right: 14px; padding-left: 11px; }
  .cell-outputs { padding: 9px; }
  .notebook-output { padding: 12px; }

  .inline-guide { grid-template-columns: 1fr; gap: 15px; padding: 20px; }
  .guide-action { width: 100%; min-height: 44px; }
  .practice-checklist { padding: 22px 19px; }
  .practice-checklist li,
  .practice-checklist label { min-height: 44px; }
  .practice-footer-actions { align-items: stretch; flex-direction: column; }
  .download-button { width: 100%; min-height: 48px; }

  .lesson-view-tree { margin-right: 4px; }
  .tree-view-link,
  .tree-artifact-link { min-height: 44px; font-size: 12px; }
}

@media (max-width: 520px) {
  .practice-hero { padding: 29px 20px; }
  .practice-kicker { margin-bottom: 18px; letter-spacing: .1em; }
  .practice-hero h1 { font-size: 34px; }
  .practice-facts { margin-top: 24px; }
  .artifact-meta { white-space: normal; }
  .notebook-head h2,
  .notebook-head h3 { white-space: normal; }
  .cell-index { max-width: 120px; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
}

.practice-briefs {
  width: min(1120px, 100%);
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  align-items: start;
  gap: 12px;
  margin: 24px auto 0;
}
.practice-brief {
  min-width: 0;
  overflow: hidden;
  background: rgba(255,255,255,.74);
  border: 1px solid #d9dbd4;
  border-radius: 16px;
  box-shadow: 0 9px 28px rgba(25,40,35,.045);
}
.practice-brief[open] { background: #fff; border-color: #bdcbc5; box-shadow: 0 14px 36px rgba(25,40,35,.075); }
.practice-brief summary {
  position: relative;
  min-height: 64px;
  display: flex;
  align-items: center;
  gap: 11px;
  padding: 14px 48px 14px 17px;
  color: #34443f;
  cursor: pointer;
  font-size: 12px;
  font-weight: 800;
  line-height: 1.45;
  list-style: none;
  user-select: none;
}
.practice-brief summary::-webkit-details-marker { display: none; }
.practice-brief summary::before {
  content: "文";
  width: 30px;
  height: 30px;
  display: grid;
  place-items: center;
  flex: 0 0 auto;
  color: #158971;
  background: #e6f5f0;
  border-radius: 9px;
  font-family: "STSong", "Songti SC", serif;
  font-size: 13px;
}
.practice-brief summary::after {
  content: "＋";
  position: absolute;
  top: 50%;
  right: 18px;
  color: #7d8a85;
  font-size: 18px;
  font-weight: 450;
  transform: translateY(-50%);
}
.practice-brief[open] summary { color: #1f3731; border-bottom: 1px solid #e3e4de; }
.practice-brief[open] summary::after { content: "−"; }
.practice-brief summary:hover { background: #f7faf8; }
.practice-brief summary > span { flex: 0 0 auto; }
.practice-brief summary > strong { min-width: 0; margin-left: auto; overflow: hidden; color: #88938e; font-size: 9px; font-weight: 650; text-overflow: ellipsis; white-space: nowrap; }
.practice-brief .prose {
  max-height: min(720px, 72dvh);
  padding: clamp(22px, 3.2vw, 36px);
  overflow: auto;
  color: #35423f;
  font-size: 14.5px;
  line-height: 1.78;
  scrollbar-width: thin;
  scrollbar-color: #c7cec9 transparent;
}
.practice-brief .prose h1 { font-size: 27px; }
.practice-brief .prose h2 { margin-top: 39px; font-size: 21px; }
.practice-brief .prose h3 { margin-top: 27px; font-size: 17px; }
.practice-brief .prose img { cursor: zoom-in; }

.notebook-markdown.prose {
  max-width: none;
  padding: clamp(22px, 3.5vw, 39px);
  color: #33403d;
  font-size: 15px;
  line-height: 1.8;
}
.notebook-markdown.prose > :first-child { margin-top: 0; }
.notebook-markdown.prose > :last-child { margin-bottom: 0; }
.notebook-markdown.prose h1 { font-size: 27px; }
.notebook-markdown.prose h2 { margin-top: 38px; font-size: 22px; }
.notebook-markdown.prose h3 { margin-top: 28px; font-size: 18px; }
.notebook-markdown.prose img { cursor: zoom-in; }
.notebook-markdown .math-source {
  max-width: 100%;
  padding: .12em .38em;
  overflow-wrap: anywhere;
  color: #264c43;
  background: #eef6f3;
  border: 1px solid #d8e8e2;
  border-radius: 6px;
  font-family: "SFMono-Regular", Consolas, monospace;
  font-size: .88em;
  font-style: normal;
}
.notebook-markdown .math-display {
  display: block;
  margin: 18px 0;
  padding: 13px 15px;
  overflow-x: auto;
  text-align: center;
  white-space: pre;
}
.notebook-markdown .math-inline { display: inline; }

.notebook-empty-output {
  min-height: 58px;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 13px 16px;
  color: #8b9490;
  background: rgba(255,255,255,.5);
  border: 1px dashed #cfd3cc;
  border-radius: 10px;
  font-size: 10px;
  line-height: 1.55;
  text-align: center;
}

@media (max-width: 820px) {
  .practice-briefs { grid-template-columns: 1fr; gap: 9px; margin-top: 18px; }
  .practice-brief summary { min-height: 56px; padding-left: 14px; }
  .practice-brief .prose { max-height: none; padding: 22px 19px; font-size: 14.5px; }
  .notebook-markdown.prose { padding: 23px 19px; font-size: 14.5px; }
  .notebook-empty-output { min-height: 64px; }
}

/* Alignment with the generated practice markup. */
.practice-title { width: min(1120px, 100%); }
.assignment-practice-title { margin-bottom: 34px; }
.assignment-practice-intro,
.assignment-document,
.source-assignment-document { width: min(1120px, 100%); margin-right: auto; margin-left: auto; }
.assignment-practice-intro {
  padding: clamp(27px, 4vw, 48px);
  color: #eaf4f0;
  background: linear-gradient(135deg, #153a31, #1b4d40 58%, #24483f);
  border-radius: 22px;
  box-shadow: 0 20px 50px rgba(20,55,46,.16);
}
.assignment-practice-intro > div { display: flex; align-items: center; justify-content: space-between; gap: 14px; color: #79cdb6; font-size: 8px; font-weight: 850; letter-spacing: .13em; }
.assignment-practice-intro em { padding: 5px 8px; color: #d8f6ec; background: rgba(255,255,255,.1); border-radius: 12px; font-style: normal; letter-spacing: .04em; }
.assignment-practice-intro h2 { max-width: 830px; margin: 24px 0 13px; font-family: "STSong", "Songti SC", serif; font-size: clamp(27px, 3.7vw, 48px); font-weight: 600; line-height: 1.22; }
.assignment-practice-intro p { max-width: 760px; margin: 0; color: #a9c2bb; font-size: 11px; line-height: 1.75; }
.assignment-document { margin-top: 24px; overflow: hidden; background: #fffefa; border: 1px solid #d9dcd5; border-radius: 19px; box-shadow: 0 12px 34px rgba(27,42,37,.06); }
.assignment-document > header { min-height: 58px; display: flex; align-items: center; justify-content: space-between; gap: 18px; padding: 0 24px; color: #276052; background: #edf5f1; border-bottom: 1px solid #dce5e0; font-size: 10px; font-weight: 800; }
.assignment-document > header strong { overflow: hidden; color: #82908b; font-size: 8px; font-weight: 650; text-overflow: ellipsis; white-space: nowrap; }
.assignment-document > .prose { padding: clamp(27px, 4.5vw, 58px); }
.source-assignment-document { margin-top: 16px; overflow: hidden; background: #f7f7f3; border: 1px solid #d8dbd4; border-radius: 16px; }
.source-assignment-document summary { min-height: 58px; display: flex; align-items: center; justify-content: space-between; gap: 18px; padding: 0 22px; color: #3e514b; cursor: pointer; font-size: 10px; font-weight: 800; list-style: none; }
.source-assignment-document summary::-webkit-details-marker { display: none; }
.source-assignment-document summary::after { content: "＋"; color: #71817c; font-size: 17px; }
.source-assignment-document[open] summary::after { content: "−"; }
.source-assignment-document summary strong { min-width: 0; margin-left: auto; overflow: hidden; color: #89938f; font-size: 8px; font-weight: 650; text-overflow: ellipsis; white-space: nowrap; }
.source-assignment-document > .prose { padding: clamp(25px, 4vw, 50px); background: #fff; border-top: 1px solid #e0e2dd; }
.lesson-header .lesson-view-switch { margin-top: 22px; }
.lesson-view-switch { width: min(620px, 100%); display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); }
.view-switch-button {
  min-width: 0;
  min-height: 62px;
  display: grid;
  grid-template-columns: 32px minmax(0, 1fr);
  grid-template-rows: auto auto;
  column-gap: 10px;
  row-gap: 2px;
  justify-content: stretch;
  padding: 9px 12px;
  text-align: left;
}
.view-switch-button > span { grid-row: 1 / 3; width: 30px; height: 30px; display: grid; place-items: center; align-self: center; color: #71807b; background: rgba(255,255,255,.58); border: 1px solid #d5dad4; border-radius: 9px; font-size: 9px; font-weight: 850; }
.view-switch-button > strong { align-self: end; overflow: hidden; font-size: 11px; line-height: 1.3; text-overflow: ellipsis; white-space: nowrap; }
.view-switch-button > small { align-self: start; overflow: hidden; color: #929b97; font-size: 8px; font-weight: 600; line-height: 1.3; text-overflow: ellipsis; white-space: nowrap; }
.view-switch-button.active > span,
.view-switch-button[aria-selected="true"] > span { color: #14352e; background: #9ee8d4; border-color: #9ee8d4; }
.view-switch-button.active > small,
.view-switch-button[aria-selected="true"] > small { color: #adc2bc; }

.practice-hero h2 { max-width: 790px; margin: 0; color: #f2f9f7; font-family: "STSong", "Songti SC", Georgia, serif; font-size: clamp(40px, 5.1vw, 68px); font-weight: 800; line-height: 1.08; letter-spacing: -.045em; }
.practice-kicker > span { color: inherit; }
.practice-kicker > em { padding: 4px 7px; color: #bed8d1; background: rgba(255,255,255,.08); border: 1px solid rgba(255,255,255,.1); border-radius: 6px; font-size: 8px; font-style: normal; letter-spacing: .06em; }
.story-step > strong { display: block; margin: 0 0 9px; color: #192925; font-size: 17px; line-height: 1.35; }

.artifact-card > p { margin: 0; color: #6f7c77; font-size: 11px; line-height: 1.55; }
.artifact-meta { display: flex; flex-wrap: wrap; gap: 5px 12px; }
.artifact-meta > span { position: relative; }
.artifact-meta > span + span::before { content: "·"; position: absolute; left: -8px; color: #afb6b3; }

.notebook-head > div > span { display: block; margin-bottom: 5px; color: #75d8bd; font-size: 8px; font-weight: 850; letter-spacing: .11em; }
.notebook-head { flex-wrap: wrap; }
.notebook-head > div { flex: 1 1 260px; }
.notebook-head dl { min-width: 330px; display: grid; grid-template-columns: repeat(4, minmax(0, 1fr)); gap: 0; flex: 1 1 330px; margin: 0; padding: 0; }
.notebook-head dl > div { min-width: 0; padding: 3px 13px; border-left: 1px solid rgba(255,255,255,.1); }
.notebook-head dt { color: #7e9991; font-size: 7px; font-weight: 800; letter-spacing: .08em; white-space: nowrap; }
.notebook-head dd { margin: 5px 0 0; overflow: hidden; color: #eff8f5; font-family: Georgia, serif; font-size: 14px; text-overflow: ellipsis; white-space: nowrap; }

.notebook-notice { justify-content: space-between; }
.notebook-notice::before { display: none; }
.notebook-notice > div { min-width: 0; display: flex; align-items: center; gap: 9px; }
.notebook-notice > div:first-child > svg { width: 20px; flex: 0 0 auto; color: #b27d18; }
.notebook-notice > div:first-child p { margin: 0; }
.notebook-notice > div:first-child strong,
.notebook-notice > div:first-child span { display: block; }
.notebook-notice > div:first-child strong { color: #68562e; font-size: 10px; }
.notebook-notice > div:first-child span { margin-top: 2px; color: #8b7a55; font-size: 9px; }
.notebook-notice > div:last-child { flex: 0 0 auto; flex-wrap: wrap; justify-content: flex-end; }
.notebook-notice > div:last-child span { padding: 4px 7px; color: #7d6c48; background: rgba(255,255,255,.58); border: 1px solid #eadab5; border-radius: 6px; font-size: 8px; font-weight: 750; }

.notebook-cell.markdown-cell { padding: 0; }
.notebook-cell.code-cell { background: #fff; border-color: #d5d9d2; }
.markdown-cell .cell-toolbar { font-family: Inter, ui-sans-serif, sans-serif; }
.markdown-cell .cell-toolbar > em,
.cell-actions > em { color: #8a9490; font-size: 8px; font-style: normal; font-weight: 700; }
.cell-source { display: block; margin: 0; padding: 0; border: 0; border-radius: 0; }
.code-lines { display: block; }
.cell-actions { min-width: 0; }
.cell-actions > em { overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }

.output-label { display: flex; align-items: center; justify-content: space-between; gap: 12px; }
.output-label > span { color: #67736e; }
.output-label > em { color: #99a19e; font-style: normal; font-weight: 650; letter-spacing: 0; text-transform: none; }
.notebook-output pre { max-width: 100%; margin: 0; overflow: auto; color: inherit; background: transparent; border: 0; font: inherit; line-height: inherit; white-space: pre-wrap; overflow-wrap: anywhere; }
.notebook-output.output-widget strong { display: block; margin-bottom: 6px; }
.notebook-output.output-widget p { margin: 0; line-height: 1.65; }

.inline-guide { display: block; }
.guide-eyebrow { display: flex; align-items: center; justify-content: space-between; gap: 12px; }
.guide-eyebrow > em { color: #7e9b92; font-size: 8px; font-style: normal; font-weight: 700; letter-spacing: 0; text-transform: none; }
.guide-body ul { display: grid; gap: 5px; padding-left: 1.25em; margin: 12px 0 0; color: #60716b; }
.guide-body li { padding-left: .15em; font-size: 11px; line-height: 1.6; }
.guide-action { margin-top: 15px; }

.practice-checklist > div:first-child > span { display: block; margin-bottom: 6px; color: #168b75; font-size: 9px; font-weight: 850; letter-spacing: .1em; text-transform: uppercase; }
.practice-checklist ol { display: grid; gap: 9px; padding: 0; margin: 0; list-style: none; }
.practice-checklist li { min-height: 52px; display: grid; grid-template-columns: 30px minmax(0, 1fr); align-items: start; gap: 11px; padding: 12px 13px; color: #53615d; background: #f8f9f5; border: 1px solid #e1e3dc; border-radius: 11px; font-size: 12px; line-height: 1.6; }
.practice-checklist li::before { display: none; }
.practice-checklist li > span { width: 27px; height: 27px; display: grid; place-items: center; color: #168f78; background: #e4f4ef; border-radius: 8px; }
.practice-checklist li > span svg { width: 14px; }
.practice-checklist li strong { display: block; color: #253933; font-size: 12px; }
.practice-checklist li p { margin: 3px 0 0; color: #77827e; font-size: 10px; }

.notebook-shell > .practice-footer-actions { width: 100%; margin: 18px 0 0; padding: 20px 22px; background: #eef0eb; border-top: 1px solid #d6d9d2; }
.practice-footer-actions > div { min-width: 0; }
.practice-footer-actions > div > strong { display: block; color: #263a34; font-size: 12px; }
.practice-footer-actions > div > p { margin: 5px 0 0; color: #79837f; font-size: 9px; line-height: 1.5; }

.tree-view-link::before,
.tree-artifact-link::before { display: none; }
.tree-view-link > span,
.tree-artifact-link > span { min-width: 33px; flex: 0 0 auto; padding: 3px 5px; color: #6f8b83; background: rgba(255,255,255,.045); border-radius: 5px; font-size: 8px; font-weight: 800; text-align: center; }
.tree-view-link > strong,
.tree-artifact-link > strong { min-width: 0; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.tree-view-link > em { margin-left: auto; color: #66817a; font-size: 8px; font-style: normal; }
.tree-artifacts { display: grid; gap: 2px; margin: 2px 0 4px 9px; padding-left: 8px; border-left: 1px solid #2f4842; }
.tree-artifact-link { padding-left: 7px; }
.tree-view-link.active > span,
.tree-artifact-link.active > span { color: #b8f5e5; background: rgba(63,193,161,.14); }

@media (max-width: 820px) {
  .assignment-practice-intro { padding: 28px 21px; border-radius: 17px; }
  .assignment-document > header { align-items: flex-start; flex-direction: column; gap: 4px; padding: 14px 18px; }
  .assignment-document > .prose,
  .source-assignment-document > .prose { padding: 24px 19px; }
  .source-assignment-document summary { padding: 0 17px; }
  .source-assignment-document summary strong { display: none; }
  .lesson-view-switch { width: 100%; max-width: 100%; }
  .view-switch-button { min-height: 66px; }
  .practice-hero h2 { font-size: clamp(35px, 9vw, 48px); }
  .notebook-head { align-items: flex-start; flex-direction: column; }
  .notebook-head dl { width: 100%; min-width: 0; }
  .notebook-head dl > div:first-child { border-left: 0; padding-left: 0; }
  .notebook-notice { align-items: flex-start; flex-direction: column; }
  .notebook-notice > div:last-child { justify-content: flex-start; }
  .guide-eyebrow { align-items: flex-start; flex-direction: column; gap: 4px; }
  .notebook-shell > .practice-footer-actions { padding: 19px 16px; }
}

@media (max-width: 520px) {
  .lesson-view-switch { grid-template-columns: 1fr; }
  .view-switch-button { min-height: 58px; }
  .practice-hero h2 { font-size: 34px; }
  .notebook-head dl { grid-template-columns: repeat(2, minmax(0, 1fr)); row-gap: 10px; }
  .notebook-head dl > div:nth-child(3) { border-left: 0; padding-left: 0; }
  .cell-actions > em { display: none; }
  .output-label { align-items: flex-start; flex-direction: column; gap: 2px; }
}

/* Semantic bilingual reader: each row owns both languages, so its height is
   naturally shared by the longer side instead of drifting during scrolling. */
.reading-paper.aligned-bilingual-paper {
  width: min(1380px, 100%);
  padding: 0;
  overflow: clip;
  background: #f9faf7;
}

.bilingual-reader { min-width: 0; }

.bilingual-reader-toolbar {
  min-height: 52px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  padding: 7px 14px 7px 20px;
  color: #75827e;
  background: #f4f6f1;
  border-bottom: 1px solid #d9ddd7;
  font-size: 9px;
  font-weight: 700;
}
.bilingual-reader-toolbar button {
  min-height: 36px;
  display: inline-flex;
  align-items: center;
  gap: 7px;
  padding: 5px 11px 5px 7px;
  color: #2d4841;
  background: #fff;
  border: 1px solid #d2d9d4;
  border-radius: 9px;
  box-shadow: 0 2px 7px rgba(24, 48, 40, .045);
  cursor: pointer;
  font: inherit;
  transition: color .16s ease, border-color .16s ease, background .16s ease, transform .16s ease;
}
.bilingual-reader-toolbar button:hover { color: #087c69; background: #f9fffc; border-color: #9ac9ba; }
.bilingual-reader-toolbar button:active { transform: translateY(1px); }
.bilingual-reader-toolbar button:focus-visible { outline: 3px solid rgba(37, 139, 116, .24); outline-offset: 2px; }
.bilingual-reader-toolbar button > span {
  min-width: 27px;
  height: 24px;
  display: grid;
  place-items: center;
  color: #49615a;
  background: #edf2ee;
  border-radius: 6px;
  font-size: 8px;
  font-weight: 850;
}
.bilingual-reader-toolbar button > b { color: #168e78; font-size: 13px; font-weight: 500; }
.bilingual-reader-toolbar button > strong { margin-left: 2px; font-size: 9px; }

.bilingual-column-head {
  position: sticky;
  z-index: 4;
  top: 0;
  display: grid;
  grid-template-columns: 72px minmax(0, 1fr) minmax(0, 1fr);
  min-height: 48px;
  align-items: center;
  color: #6e7d78;
  background: rgba(250, 251, 248, .96);
  border-bottom: 1px solid #d9ddd7;
  box-shadow: 0 7px 18px rgba(26, 42, 37, .035);
  backdrop-filter: blur(12px);
  font-size: 8px;
  font-weight: 850;
  letter-spacing: .09em;
}
.bilingual-column-head > * { height: 100%; display: flex; align-items: center; padding: 0 24px; }
.bilingual-column-head > span { justify-content: center; padding: 0 8px; color: #8d9894; border-right: 1px solid #e1e4de; }
.bilingual-column-head > strong + strong { border-left: 1px solid #e1e4de; }
.bilingual-column-label-zh { color: #087f6d; }
.bilingual-column-label-en { color: #3a55c6; }

.bilingual-pairs { background: #f6f7f3; }
.bilingual-pair {
  position: relative;
  display: grid;
  grid-template-columns: 72px minmax(0, 1fr) minmax(0, 1fr);
  min-width: 0;
  border-bottom: 1px solid #dde0da;
  scroll-margin-top: 62px;
  transition: box-shadow .18s ease;
}
.bilingual-pair:last-child { border-bottom: 0; }
.bilingual-pair:focus { outline: none; }
.bilingual-pair:focus-visible {
  z-index: 2;
  outline: 3px solid rgba(56, 88, 233, .36);
  outline-offset: -3px;
}
.bilingual-pair-rail {
  min-width: 0;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: flex-start;
  gap: 7px;
  padding: 22px 7px;
  color: #87918d;
  background: #eff1ec;
  border-right: 1px solid #dde0da;
  cursor: pointer;
  transition: color .18s ease, background .18s ease;
}
.bilingual-pair-rail strong {
  color: inherit;
  font-family: "SFMono-Regular", Consolas, monospace;
  font-size: 9px;
  letter-spacing: .04em;
}
.bilingual-pair-rail span {
  max-width: 58px;
  padding: 3px 5px;
  overflow: hidden;
  color: #9aa29f;
  background: rgba(255, 255, 255, .7);
  border: 1px solid #dfe2dc;
  border-radius: 10px;
  font-size: 7px;
  font-weight: 750;
  line-height: 1.25;
  text-overflow: ellipsis;
  white-space: nowrap;
}
.bilingual-side {
  position: relative;
  min-width: 0;
  padding: clamp(23px, 3vw, 38px);
  background: #fffefa;
  transition: background .18s ease, box-shadow .18s ease;
}
.bilingual-side + .bilingual-side { border-left: 1px solid #e1e3dd; }
.bilingual-side-en { background: #fdfdfb; }
.bilingual-side-label {
  display: none;
  width: max-content;
  margin-bottom: 12px;
  padding: 4px 7px;
  color: #77847f;
  background: #eef1ed;
  border-radius: 5px;
  font-family: Inter, ui-sans-serif, sans-serif;
  font-size: 7px;
  font-weight: 850;
  letter-spacing: .06em;
}
.alignment-zh-only .bilingual-side-label,
.alignment-en-only .bilingual-side-label { display: inline-flex; }
.alignment-zh-only .bilingual-side-zh .bilingual-side-label { color: #a16615; background: #fff2d7; }
.alignment-en-only .bilingual-side-en .bilingual-side-label { color: #3854c2; background: #ebefff; }

.bilingual-prose { font-size: 15px; line-height: 1.78; }
.bilingual-side-en .bilingual-prose { color: #33403d; font-family: Georgia, "Times New Roman", serif; }
.bilingual-prose .aligned-block { min-width: 0; }
.bilingual-prose .aligned-block + .aligned-block { margin-top: 14px; }
.bilingual-prose .aligned-block > :first-child { margin-top: 0; }
.bilingual-prose .aligned-block > :last-child { margin-bottom: 0; }
.bilingual-prose h1 { margin: 0; padding-bottom: 13px; font-size: 26px; }
.bilingual-prose h2 { margin: 0; font-size: 20px; }
.bilingual-prose h3 { margin: 0; font-size: 17px; }
.bilingual-prose p:last-child,
.bilingual-prose ul:last-child,
.bilingual-prose ol:last-child,
.bilingual-prose blockquote:last-child,
.bilingual-prose pre:last-child,
.bilingual-prose table:last-child,
.bilingual-prose img:last-child { margin-bottom: 0; }
.bilingual-prose table { display: block; max-width: 100%; overflow-x: auto; }
.bilingual-prose img { max-height: 540px; object-fit: contain; }
.pair-type-heading .bilingual-side { display: flex; align-items: center; min-height: 96px; background: #f9faf6; }
.pair-type-heading .bilingual-side-label { flex: 0 0 auto; margin-right: 12px; margin-bottom: 0; }
.pair-type-heading .bilingual-prose { width: 100%; }
.pair-type-heading .bilingual-side.is-empty .bilingual-empty { width: 100%; }
.pair-type-separator .bilingual-side { padding-top: 15px; padding-bottom: 15px; }
.pair-type-separator .bilingual-empty { min-height: 42px; }

.bilingual-pair:hover .bilingual-side,
.bilingual-pair:focus-within .bilingual-side { background: #f3faf7; }
.bilingual-pair:hover .bilingual-side-en,
.bilingual-pair:focus-within .bilingual-side-en { background: #f4f6ff; }
.bilingual-pair:hover .bilingual-pair-rail,
.bilingual-pair:focus-within .bilingual-pair-rail { color: #137c6a; background: #dff2eb; }
.bilingual-pair.is-locked { z-index: 1; box-shadow: inset 4px 0 #12a286, 0 8px 24px rgba(24, 74, 62, .09); }
.bilingual-pair.is-locked .bilingual-side { background: #eaf8f3; }
.bilingual-pair.is-locked .bilingual-side-en { background: #eef1ff; }
.bilingual-pair.is-locked .bilingual-pair-rail { color: #fff; background: #168e78; border-right-color: #168e78; }
.bilingual-pair.is-locked .bilingual-pair-rail span { color: #d9fff5; background: rgba(255, 255, 255, .12); border-color: rgba(255, 255, 255, .18); }
.alignment-zh-only .bilingual-pair-rail span { color: #9e6517; background: #fff2d7; border-color: #f0d9a7; }
.alignment-en-only .bilingual-pair-rail span { color: #3b54bd; background: #ebefff; border-color: #d2dafa; }
.alignment-zh-only.is-uncalibrated-pair .bilingual-pair-rail span { color: #a24937; background: #ffebe5; border-color: #efc5ba; }
.alignment-zh-only.is-uncalibrated-pair .bilingual-side-zh .bilingual-side-label { color: #a24937; background: #ffebe5; }
.alignment-zh-only.is-uncalibrated-pair .bilingual-side-en .bilingual-side-label { color: #7b645e; background: #f2ece9; }
.bilingual-pair.is-locked.alignment-zh-only .bilingual-pair-rail span,
.bilingual-pair.is-locked.alignment-en-only .bilingual-pair-rail span { color: #fff; background: rgba(255,255,255,.14); border-color: rgba(255,255,255,.2); }

.bilingual-empty {
  min-height: 78px;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 9px;
  color: #9aa29f;
  background: repeating-linear-gradient(-45deg, transparent 0, transparent 8px, rgba(117, 128, 123, .035) 8px, rgba(117, 128, 123, .035) 9px);
  border: 1px dashed #d8dcd6;
  border-radius: 10px;
}
.bilingual-empty span { width: 28px; height: 28px; display: grid; place-items: center; color: #8e9994; background: #f0f2ee; border-radius: 8px; font-size: 8px; font-weight: 850; }
.bilingual-empty p { margin: 0; font-size: 9px; font-weight: 700; }

.bilingual-reader-note {
  display: flex;
  align-items: flex-start;
  gap: 11px;
  padding: 20px clamp(24px, 4vw, 52px) 24px;
  color: #72807b;
  background: #eef0eb;
  border-top: 1px solid #d9dcd6;
  font-size: 9px;
  line-height: 1.65;
}
.bilingual-reader-note span { flex: 0 0 auto; padding: 3px 6px; color: #087d6c; background: #dcefe9; border-radius: 5px; font-weight: 850; }
.bilingual-reader-note p { margin: 0; }

.bilingual-loading { min-height: 660px; padding: clamp(30px, 4vw, 52px); background: #fafbf8; }
.bilingual-loading-head { display: flex; align-items: center; gap: 18px; margin-bottom: 38px; }
.bilingual-loading-head .loading-orbit { width: 45px; height: 45px; flex: 0 0 auto; }
.bilingual-loading-head .loading-orbit i { width: 7px; height: 7px; }
.bilingual-loading-head .loading-orbit i:nth-child(1) { top: -4px; left: 18px; }
.bilingual-loading-head strong { display: block; color: #243630; font-size: 14px; }
.bilingual-loading-head p { margin: 5px 0 0; color: #7b8782; font-size: 10px; line-height: 1.55; }
.bilingual-skeleton-pair { display: grid; grid-template-columns: 52px 1fr 1fr; gap: 18px; min-height: 108px; padding: 17px 0; border-top: 1px solid #e1e4de; }
.bilingual-skeleton-pair i { padding-top: 8px; color: #abb2af; font-family: Consolas, monospace; font-size: 8px; font-style: normal; }
.bilingual-skeleton-pair span { border-radius: 10px; background: linear-gradient(100deg, #eceee9 20%, #f7f8f5 38%, #eceee9 58%); background-size: 220% 100%; animation: bilingual-shimmer 1.45s linear infinite; }
@keyframes bilingual-shimmer { to { background-position-x: -220%; } }

.bilingual-fallback-notice {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 20px;
  margin-bottom: 28px;
  padding: 15px 17px;
  color: #735c2f;
  background: #fff8e8;
  border: 1px solid #ead7ad;
  border-radius: 12px;
}
.bilingual-fallback-notice strong { display: block; font-size: 11px; }
.bilingual-fallback-notice p { margin: 4px 0 0; color: #8a7958; font-size: 9px; line-height: 1.5; }
.bilingual-fallback-notice button { flex: 0 0 auto; min-height: 36px; padding: 0 12px; color: #735513; background: #fff; border: 1px solid #dfc890; border-radius: 8px; cursor: pointer; font-size: 9px; font-weight: 800; }
.bilingual-fallback-notice button:hover { background: #fffdf7; border-color: #bc9a50; }

@media (max-width: 820px) {
  .reading-paper.aligned-bilingual-paper { padding: 0; border-radius: 16px; }
  .bilingual-reader-toolbar { position: sticky; z-index: 4; top: 0; padding-left: 15px; }
  .bilingual-reader-toolbar > span { display: none; }
  .bilingual-reader-toolbar button { width: 100%; justify-content: center; }
  .bilingual-column-head { display: none; }
  .bilingual-pair { grid-template-columns: minmax(0, 1fr); scroll-margin-top: 74px; }
  .bilingual-pair-rail {
    min-height: 36px;
    flex-direction: row;
    justify-content: space-between;
    padding: 8px 15px;
    border-right: 0;
    border-bottom: 1px solid #dfe2dc;
  }
  .bilingual-pair-rail span { max-width: none; }
  .bilingual-side { padding: 20px 18px 23px; }
  .bilingual-side + .bilingual-side { border-top: 1px solid #e0e3dd; border-left: 0; }
  .bilingual-side-label { display: inline-flex; margin-bottom: 12px; }
  .bilingual-prose { font-size: 15.5px; line-height: 1.8; }
  .bilingual-prose h1 { font-size: 25px; }
  .bilingual-prose h2 { font-size: 20px; }
  .pair-type-heading .bilingual-side { min-height: 74px; }
  .bilingual-reader-note { padding: 18px; }
  .bilingual-loading { min-height: 520px; padding: 28px 20px; }
  .bilingual-skeleton-pair { grid-template-columns: 42px 1fr; }
  .bilingual-skeleton-pair span:last-child { grid-column: 2; }
  .bilingual-fallback-notice { align-items: stretch; flex-direction: column; }
  .bilingual-fallback-notice button { min-height: 42px; }
}

@media (max-width: 520px) {
  .bilingual-side { padding-right: 15px; padding-left: 15px; }
  .bilingual-prose { font-size: 15px; }
}