:root {
  --ink: #29263a;
  --muted: #6f6a7f;
  --paper: #fbfaf6;
  --surface: #ffffff;
  --line: #e8e3ef;
  --purple: #5b4b8a;
  --purple-dark: #40336d;
  --purple-soft: #eee9f8;
  --green: #2c7a68;
  --green-soft: #e6f4ef;
  --amber: #c47b27;
  --amber-soft: #fff3dd;
  --rose: #a94e66;
  --shadow: 0 18px 55px rgba(54, 42, 78, 0.1);
  --radius: 22px;
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  color: var(--ink);
  background:
    radial-gradient(circle at 80% 0%, rgba(91, 75, 138, 0.08), transparent 28rem),
    var(--paper);
  font-family: "Microsoft YaHei", "PingFang SC", "Noto Sans CJK SC", system-ui, sans-serif;
  line-height: 1.65;
}

button, textarea, input { font: inherit; }
button { color: inherit; }
a { color: inherit; text-decoration: none; }

.app-shell { min-height: 100vh; }

.sidebar {
  position: fixed;
  inset: 0 auto 0 0;
  z-index: 10;
  display: flex;
  width: 292px;
  flex-direction: column;
  padding: 26px 20px 18px;
  overflow-y: auto;
  color: #f8f7ff;
  background:
    linear-gradient(160deg, rgba(255,255,255,.08), transparent 35%),
    #322a53;
}

.brand { display: flex; align-items: center; gap: 12px; padding: 0 8px 22px; }
.brand-mark { display: grid; width: 47px; height: 47px; place-items: center; border-radius: 15px; background: #fff; }
.brand-mark svg { width: 32px; fill: none; stroke: var(--purple); stroke-width: 3; stroke-linecap: round; stroke-linejoin: round; }
.brand strong { display: block; font-size: 20px; letter-spacing: .04em; }
.brand small { display: block; margin-top: 1px; color: #c9c3de; font-size: 12px; }

.today-card { padding: 16px; margin-bottom: 20px; border: 1px solid rgba(255,255,255,.12); border-radius: 18px; background: rgba(255,255,255,.08); }
.eyebrow { display: block; margin-bottom: 5px; color: #bab3d5; font-size: 11px; letter-spacing: .16em; text-transform: uppercase; }
.today-card strong { display: block; font-size: 15px; }
.today-card small { color: #c9c3de; font-size: 12px; }
.mini-progress { height: 6px; margin: 13px 0 6px; overflow: hidden; border-radius: 99px; background: rgba(255,255,255,.12); }
.mini-progress span { display: block; width: 0; height: 100%; border-radius: inherit; background: #8dd6bd; transition: width .4s ease; }

.coach-link { display: flex; align-items: center; gap: 10px; padding: 11px; margin: -5px 0 14px; border: 1px solid rgba(141,214,189,.24); border-radius: 14px; color: #e5fff6; background: rgba(141,214,189,.09); transition: .2s ease; }
.coach-link:hover, .coach-link.active { border-color: rgba(141,214,189,.55); background: rgba(141,214,189,.17); }
.coach-link-icon { display: grid; flex: 0 0 34px; height: 34px; place-items: center; border-radius: 10px; color: #173e35; background: #8dd6bd; font-size: 11px; font-weight: 900; }
.coach-link strong, .coach-link small { display: block; }
.coach-link strong { font-size: 13px; }
.coach-link small { color: #b9d8ce; font-size: 9px; }

.unit-nav { display: grid; gap: 5px; }
.nav-chapter { display: grid; gap: 3px; }
.chapter-nav-link { display: flex; align-items: center; gap: 10px; padding: 9px 10px; border-radius: 12px; color: #c9c3de; transition: .2s ease; }
.chapter-nav-link:hover, .nav-chapter.active > .chapter-nav-link { color: white; background: rgba(255,255,255,.1); }
.chapter-nav-link .number { display: grid; flex: 0 0 30px; height: 30px; place-items: center; border: 1px solid rgba(255,255,255,.18); border-radius: 9px; font-size: 10px; }
.chapter-nav-link strong, .chapter-nav-link small { display: block; }
.chapter-nav-link strong { font-size: 12px; }
.chapter-nav-link small { color: #9890b5; font-size: 9px; }
.chapter-nav-link.done .number { color: #173e35; border-color: transparent; background: #8dd6bd; }
.chapter-unit-links { display: grid; gap: 2px; padding: 3px 0 7px 18px; border-left: 1px solid rgba(255,255,255,.12); margin-left: 25px; }
.chapter-unit-links .unit-link { padding: 6px 8px; font-size: 11px; }
.chapter-unit-links .unit-link .number { flex-basis: 24px; height: 24px; border-radius: 7px; font-size: 8px; }
.unit-link { display: flex; align-items: center; gap: 11px; padding: 10px 11px; border-radius: 12px; color: #c9c3de; font-size: 13px; transition: .2s ease; }
.unit-link:hover, .unit-link.active { color: white; background: rgba(255,255,255,.1); }
.unit-link .number { display: grid; flex: 0 0 28px; height: 28px; place-items: center; border: 1px solid rgba(255,255,255,.18); border-radius: 9px; font-size: 11px; }
.unit-link.done .number { color: #173e35; border-color: transparent; background: #8dd6bd; }

.sidebar-footer { display: grid; gap: 3px; padding: 18px 10px 0; margin-top: auto; color: #9890b5; font-size: 10px; }
.text-button { width: fit-content; padding: 0; border: 0; color: #c9c3de; background: none; cursor: pointer; font-size: 12px; }
.text-button:hover { color: white; }

.main { min-height: 100vh; margin-left: 292px; padding: 42px clamp(28px, 5vw, 76px) 100px; }
.content-wrap { width: min(1100px, 100%); margin: 0 auto; }

.hero { display: grid; grid-template-columns: 1.25fr .75fr; gap: 28px; align-items: stretch; margin-bottom: 34px; }
.hero-copy, .hero-visual { overflow: hidden; border: 1px solid var(--line); border-radius: 30px; background: var(--surface); box-shadow: var(--shadow); }
.hero-copy { padding: clamp(30px, 5vw, 56px); }
.hero-copy .overline, .lesson-overline { color: var(--green); font-size: 12px; font-weight: 700; letter-spacing: .14em; }
.hero h1 { max-width: 680px; margin: 10px 0 14px; font-family: Georgia, "Songti SC", serif; font-size: clamp(35px, 4vw, 56px); line-height: 1.14; letter-spacing: -.02em; }
.hero p { max-width: 640px; margin: 0 0 24px; color: var(--muted); font-size: 16px; }
.hero-actions { display: flex; flex-wrap: wrap; gap: 11px; }

.primary-button, .secondary-button {
  display: inline-flex;
  min-height: 46px;
  align-items: center;
  justify-content: center;
  padding: 0 20px;
  border-radius: 13px;
  cursor: pointer;
  font-weight: 700;
  transition: transform .18s ease, box-shadow .18s ease, background .18s ease;
}
.primary-button { border: 1px solid var(--purple); color: white; background: var(--purple); box-shadow: 0 8px 20px rgba(91,75,138,.22); }
.primary-button:hover { transform: translateY(-1px); background: var(--purple-dark); }
.primary-button:disabled { opacity: .55; cursor: wait; transform: none; }
.secondary-button { border: 1px solid var(--line); background: white; }
.secondary-button:hover { border-color: #ccc2dc; background: var(--purple-soft); }

.hero-visual { position: relative; display: grid; min-height: 330px; place-items: center; background: linear-gradient(145deg, #ece8f7, #f7f2e8); }
.hero-visual::before, .hero-visual::after { position: absolute; content: ""; border-radius: 50%; }
.hero-visual::before { width: 220px; height: 220px; background: rgba(255,255,255,.54); }
.hero-visual::after { right: 15%; bottom: 12%; width: 75px; height: 75px; border: 1px dashed rgba(91,75,138,.35); }
.big-vector { position: relative; z-index: 1; width: 70%; }
.big-vector svg { width: 100%; overflow: visible; }
.big-vector line { stroke: var(--purple); stroke-width: 7; stroke-linecap: round; }
.big-vector path { fill: var(--purple); }
.big-vector circle { fill: var(--green); }
.big-vector span { display: block; margin-top: 20px; color: var(--purple-dark); font-family: Georgia, serif; font-size: 22px; text-align: center; }

.stats { display: grid; grid-template-columns: repeat(3, 1fr); gap: 14px; margin-bottom: 40px; }
.stat { padding: 18px 20px; border: 1px solid var(--line); border-radius: 17px; background: rgba(255,255,255,.7); }
.stat strong { display: block; font-family: Georgia, serif; font-size: 25px; }
.stat span { color: var(--muted); font-size: 12px; }

.coach-banner { display: grid; grid-template-columns: auto 1fr auto; gap: 14px; align-items: center; padding: 18px 20px; margin: -19px 0 38px; border: 1px solid #c7ded5; border-radius: 18px; color: #173e35; background: linear-gradient(120deg, #e6f4ef, #f5f2fb); transition: transform .2s ease, box-shadow .2s ease; }
.coach-banner:hover { transform: translateY(-2px); box-shadow: 0 12px 30px rgba(44,122,104,.1); }
.coach-banner-icon { display: grid; width: 43px; height: 43px; place-items: center; border-radius: 13px; color: white; background: var(--green); font-size: 12px; font-weight: 900; }
.coach-banner strong, .coach-banner small { display: block; }
.coach-banner strong { font-size: 15px; }
.coach-banner small { margin-top: 2px; color: #52786d; font-size: 11px; }
.coach-banner-arrow { color: var(--green); font-size: 12px; font-weight: 700; }
.coach-banner.advanced-entry { margin-top: -26px; border-color: #d3c9e3; color: #3f315f; background: linear-gradient(120deg, #f0ebf8, #f8f6ef); }
.coach-banner.advanced-entry .coach-banner-icon { background: var(--purple); }
.coach-banner.advanced-entry small, .coach-banner.advanced-entry .coach-banner-arrow { color: #756394; }
.coach-banner.high-stage-entry { margin-top: -26px; border-color: #c7d8e7; color: #24435d; background: linear-gradient(120deg, #e9f2f8, #f8f6ef); }
.coach-banner.high-stage-entry .coach-banner-icon { background: #285b83; font-size: 10px; }
.coach-banner.high-stage-entry small, .coach-banner.high-stage-entry .coach-banner-arrow { color: #4c718e; }

.section-heading { display: flex; align-items: end; justify-content: space-between; gap: 20px; margin: 34px 0 17px; }
.section-heading h2 { margin: 0; font-family: Georgia, "Songti SC", serif; font-size: 28px; }
.section-heading p { margin: 0; color: var(--muted); font-size: 13px; }

.unit-grid { display: grid; grid-template-columns: repeat(2, minmax(0,1fr)); gap: 17px; }
.chapter-grid { display: grid; grid-template-columns: repeat(2, minmax(0,1fr)); gap: 17px; }
.chapter-card { position: relative; min-height: 190px; padding: 25px; overflow: hidden; border: 1px solid var(--line); border-radius: 24px; background: var(--surface); transition: transform .2s ease, box-shadow .2s ease; }
.chapter-card:hover { transform: translateY(-3px); box-shadow: var(--shadow); }
.chapter-card::after { position: absolute; right: -45px; top: -55px; width: 160px; height: 160px; content: ""; border-radius: 50%; background: var(--chapter-soft); }
.chapter-card-top { position: relative; z-index: 1; display: flex; align-items: center; justify-content: space-between; color: var(--chapter-color); font-size: 12px; font-weight: 800; }
.chapter-card-top strong { font-family: Georgia, serif; font-size: 25px; }
.chapter-card h3 { position: relative; z-index: 1; margin: 18px 0 6px; font-family: Georgia, "Songti SC", serif; font-size: 23px; }
.chapter-card p { min-height: 42px; margin: 0 0 17px; color: var(--muted); font-size: 12px; }
.unit-card { position: relative; padding: 24px; overflow: hidden; border: 1px solid var(--line); border-radius: var(--radius); background: var(--surface); transition: transform .2s ease, box-shadow .2s ease; }
.unit-card:hover { transform: translateY(-3px); box-shadow: var(--shadow); }
.unit-card::after { position: absolute; right: -30px; top: -40px; width: 125px; height: 125px; content: ""; border-radius: 50%; background: var(--unit-soft, var(--purple-soft)); opacity: .8; }
.unit-card-top { position: relative; z-index: 1; display: flex; align-items: center; justify-content: space-between; }
.unit-index { display: grid; width: 42px; height: 42px; place-items: center; border-radius: 13px; color: var(--unit-color, var(--purple)); background: var(--unit-soft, var(--purple-soft)); font-weight: 800; }
.status-chip { padding: 5px 9px; border-radius: 99px; color: var(--muted); background: #f3f1f5; font-size: 11px; }
.status-chip.done { color: var(--green); background: var(--green-soft); }
.unit-card h3 { position: relative; z-index: 1; margin: 17px 0 7px; font-size: 19px; }
.unit-card p { min-height: 50px; margin: 0 0 18px; color: var(--muted); font-size: 13px; }
.unit-progress { height: 7px; overflow: hidden; border-radius: 99px; background: #eeeaf1; }
.unit-progress span { display: block; height: 100%; border-radius: inherit; background: var(--unit-color, var(--purple)); }
.unit-meta { display: flex; justify-content: space-between; margin-top: 8px; color: var(--muted); font-size: 11px; }

.resume-card { display: flex; align-items: center; justify-content: space-between; gap: 20px; padding: 22px 25px; margin-top: 36px; border-radius: var(--radius); color: #173e35; background: var(--green-soft); }
.resume-card h3 { margin: 0 0 3px; font-size: 17px; }
.resume-card p { margin: 0; color: #52786d; font-size: 12px; }

.crumbs { display: flex; align-items: center; gap: 7px; margin-bottom: 24px; color: var(--muted); font-size: 12px; }
.crumbs a:hover { color: var(--purple); }

.lesson-header { display: grid; grid-template-columns: 1fr auto; gap: 24px; padding-bottom: 28px; border-bottom: 1px solid var(--line); }
.lesson-header h1 { margin: 7px 0 9px; font-family: Georgia, "Songti SC", serif; font-size: clamp(30px, 4vw, 46px); line-height: 1.2; }
.lesson-header p { max-width: 720px; margin: 0; color: var(--muted); }
.lesson-time { align-self: start; padding: 9px 13px; border-radius: 12px; color: var(--green); background: var(--green-soft); font-size: 12px; font-weight: 700; }

.lesson-layout { display: grid; grid-template-columns: minmax(0, 1fr) 260px; gap: 30px; margin-top: 28px; }
.lesson-body { min-width: 0; }
.lesson-toc { position: sticky; top: 24px; height: fit-content; padding: 18px; border: 1px solid var(--line); border-radius: 17px; background: rgba(255,255,255,.8); }
.lesson-toc strong { font-size: 13px; }
.lesson-toc .toc-link { display: block; width: 100%; padding: 6px 0; border: 0; color: var(--muted); background: none; cursor: pointer; font-size: 12px; text-align: left; }
.lesson-toc .toc-link:hover { color: var(--purple); }

.learning-card { padding: clamp(22px, 4vw, 34px); margin-bottom: 18px; border: 1px solid var(--line); border-radius: var(--radius); background: var(--surface); }
.learning-card h2 { display: flex; align-items: center; gap: 10px; margin: 0 0 18px; font-family: Georgia, "Songti SC", serif; font-size: 23px; }
.step-number { display: grid; flex: 0 0 30px; height: 30px; place-items: center; border-radius: 10px; color: var(--purple); background: var(--purple-soft); font-family: "Microsoft YaHei", sans-serif; font-size: 12px; }
.micro-copy { color: #413d4e; font-size: 17px; line-height: 1.9; }
.micro-copy strong { color: var(--purple-dark); }
.key-points { display: grid; gap: 10px; padding: 0; margin: 18px 0 0; list-style: none; }
.key-points li { position: relative; padding: 10px 14px 10px 37px; border-radius: 12px; background: #f8f6fb; }
.key-points li::before { position: absolute; left: 14px; top: 12px; content: "✓"; color: var(--green); font-weight: 900; }

.worked-example { padding: 18px; border-left: 4px solid var(--amber); border-radius: 0 14px 14px 0; background: var(--amber-soft); }
.worked-example .question { margin-bottom: 13px; font-weight: 700; }
.worked-example ol { margin: 0; padding-left: 22px; }
.worked-example li { margin: 7px 0; }

.vector-lab { display: grid; grid-template-columns: minmax(280px, 1fr) 210px; gap: 20px; align-items: center; }
.vector-canvas { width: 100%; aspect-ratio: 1.5; border: 1px solid #ddd6e7; border-radius: 16px; background: #fbfafd; cursor: crosshair; touch-action: none; }
.lab-readout { display: grid; gap: 10px; }
.lab-readout .coordinate { padding: 18px; border-radius: 16px; color: white; background: var(--purple); text-align: center; }
.lab-readout .coordinate strong { display: block; font-family: Georgia, serif; font-size: 28px; }
.lab-readout p { margin: 0; color: var(--muted); font-size: 12px; }

.quiz-list { display: grid; gap: 17px; }
.quiz-card { padding: 19px; border: 1px solid var(--line); border-radius: 16px; background: #fdfcfe; }
.quiz-card.correct { border-color: #9ecdbf; background: #f3faf7; }
.quiz-card.incorrect { border-color: #dfb0bc; background: #fff7f8; }
.quiz-question { margin: 0 0 13px; font-weight: 700; }
.choices { display: grid; grid-template-columns: repeat(2, minmax(0,1fr)); gap: 9px; }
.choice { padding: 11px 13px; border: 1px solid #ded8e6; border-radius: 11px; background: white; cursor: pointer; text-align: left; transition: .15s ease; }
.choice:hover { border-color: #9e91bd; background: var(--purple-soft); }
.choice.selected { color: white; border-color: var(--purple); background: var(--purple); }
.choice.wrong-choice { color: #813f50; border-color: #dfb0bc; background: #f8e4e9; text-decoration: line-through; opacity: .78; }
.choice:disabled { cursor: default; }
.feedback { display: none; padding: 12px 14px; margin-top: 12px; border-radius: 11px; font-size: 13px; }
.feedback.show { display: block; }
.correct .feedback { color: #245f51; background: #deefe9; }
.incorrect .feedback { color: #813f50; background: #f8e4e9; }
.hint-button { padding: 6px 0; margin-top: 8px; border: 0; color: var(--purple); background: none; cursor: pointer; font-size: 12px; }

.lesson-result { display: none; padding: 26px; margin-top: 18px; border-radius: var(--radius); background: linear-gradient(145deg, #e7f4ef, #f7f2e8); }
.lesson-result.show { display: block; }
.lesson-result h3 { margin: 0 0 5px; font-size: 21px; }
.lesson-result p { margin: 0 0 17px; color: #526e66; }

.unit-page-head { padding: 30px; border-radius: 28px; color: white; background: linear-gradient(135deg, var(--purple-dark), var(--purple)); }
.unit-page-head h1 { margin: 8px 0; font-family: Georgia, "Songti SC", serif; font-size: 36px; }
.unit-page-head p { max-width: 720px; margin: 0; color: #ddd8ed; }
.lesson-list { display: grid; gap: 11px; margin-top: 23px; }
.lesson-row { display: grid; grid-template-columns: 45px 1fr auto; gap: 14px; align-items: center; padding: 17px; border: 1px solid var(--line); border-radius: 16px; background: var(--surface); }
.lesson-row:hover { border-color: #cfc5de; box-shadow: 0 10px 28px rgba(54,42,78,.07); }
.lesson-row .lesson-number { display: grid; height: 40px; place-items: center; border-radius: 12px; color: var(--purple); background: var(--purple-soft); font-weight: 800; }
.lesson-row h3 { margin: 0 0 2px; font-size: 15px; }
.lesson-row p { margin: 0; color: var(--muted); font-size: 11px; }
.lesson-state { color: var(--muted); font-size: 11px; }
.lesson-state.done { color: var(--green); font-weight: 700; }

.summary-card { padding: 26px; margin-top: 26px; border: 1px solid #c7ded5; border-radius: var(--radius); background: var(--green-soft); }
.summary-card h2 { margin: 0 0 8px; font-size: 22px; }
.summary-card p { margin: 0 0 16px; color: #52786d; }
.chapter-page-head { display: grid; grid-template-columns: 1fr auto; gap: 30px; align-items: center; padding: clamp(30px, 5vw, 48px); border-radius: 28px; color: white; background: radial-gradient(circle at 88% 10%, rgba(255,255,255,.16), transparent 18rem), linear-gradient(135deg, color-mix(in srgb, var(--chapter-color), #202335 38%), var(--chapter-color)); box-shadow: var(--shadow); }
.chapter-page-head h1 { margin: 8px 0; font-family: Georgia, "Songti SC", serif; font-size: clamp(32px, 4vw, 46px); }
.chapter-page-head p { margin: 0; color: rgba(255,255,255,.76); }
.chapter-page-progress { min-width: 160px; padding: 20px; border: 1px solid rgba(255,255,255,.18); border-radius: 18px; background: rgba(255,255,255,.1); text-align: center; }
.chapter-page-progress strong, .chapter-page-progress span { display: block; }
.chapter-page-progress strong { font-family: Georgia, serif; font-size: 29px; }
.chapter-page-progress span { color: rgba(255,255,255,.72); font-size: 10px; }

.coach-page { --coach-navy: #26394b; }
.coach-hero { display: grid; grid-template-columns: 1fr auto; gap: 28px; align-items: center; padding: clamp(28px, 5vw, 48px); overflow: hidden; border-radius: 28px; color: white; background: radial-gradient(circle at 85% 10%, rgba(141,214,189,.2), transparent 16rem), linear-gradient(135deg, #26394b, #3e356a); box-shadow: var(--shadow); }
.coach-hero h1 { margin: 8px 0 13px; font-family: Georgia, "Songti SC", serif; font-size: clamp(31px, 4vw, 47px); line-height: 1.18; }
.coach-hero p { max-width: 650px; margin: 0; color: #cad4dc; font-size: 13px; }
.coach-today { min-width: 190px; padding: 24px; border: 1px solid rgba(255,255,255,.14); border-radius: 21px; background: rgba(255,255,255,.08); text-align: center; }
.coach-today span, .coach-today small { display: block; color: #bad6ce; font-size: 11px; }
.coach-today strong { display: block; margin: 6px 0; font-family: Georgia, serif; font-size: 34px; }
.coach-stats { display: grid; grid-template-columns: repeat(4, 1fr); gap: 13px; margin: 17px 0; }
.coach-stat { padding: 18px; border: 1px solid var(--line); border-radius: 17px; background: white; }
.coach-stat > span { color: var(--muted); font-size: 11px; }
.coach-stat strong { display: block; margin: 5px 0 1px; font-family: Georgia, serif; font-size: 27px; }
.coach-stat strong small { color: var(--muted); font-family: inherit; font-size: 13px; }
.coach-stat p { margin: 0; color: var(--muted); font-size: 10px; }
.coach-ai-card { display: grid; grid-template-columns: 1fr auto; gap: 18px 28px; align-items: center; padding: 25px; border: 1px solid #d3c9e3; border-radius: 22px; background: linear-gradient(135deg, #f0ebf8, #f8f6ef); }
.coach-ai-copy h2 { margin: 7px 0 5px; font-size: 21px; }
.coach-ai-copy p { max-width: 720px; margin: 0; color: var(--muted); font-size: 12px; }
.coach-ai-badge { padding: 4px 8px; border-radius: 99px; color: white; background: var(--purple); font-size: 9px; font-weight: 800; letter-spacing: .1em; }
.coach-ai-result { grid-column: 1 / -1; }
.coach-grid { display: grid; grid-template-columns: minmax(0, 1.65fr) minmax(270px, .75fr); gap: 17px; align-items: start; margin-top: 17px; }
.coach-section { padding: 24px; border: 1px solid var(--line); border-radius: 22px; background: white; }
.coach-section .section-heading { margin: 0 0 17px; }
.coach-section .section-heading h2 { font-size: 22px; }
.mastery-list { display: grid; gap: 20px; }
.mastery-chapter { display: grid; gap: 18px; padding-top: 4px; }
.mastery-chapter + .mastery-chapter { padding-top: 22px; border-top: 2px solid var(--line); }
.mastery-chapter > h2 { margin: 0; color: var(--purple-dark); font-family: Georgia, "Songti SC", serif; font-size: 18px; }
.mastery-unit h3 { padding-bottom: 8px; margin: 0; border-bottom: 1px solid var(--line); font-size: 13px; }
.mastery-row { display: grid; grid-template-columns: minmax(150px, 1.2fr) minmax(90px, 1fr) 68px; gap: 12px; align-items: center; padding: 10px 2px; border-bottom: 1px solid #f1eef4; }
.mastery-row:hover .mastery-name { color: var(--purple); }
.mastery-name { font-size: 12px; font-weight: 700; }
.mastery-name small, .mastery-value small { display: block; color: var(--muted); font-size: 9px; font-weight: 400; }
.mastery-bar { height: 7px; overflow: hidden; border-radius: 99px; background: #eeeaf1; }
.mastery-bar i { display: block; height: 100%; border-radius: inherit; background: linear-gradient(90deg, #9e91bd, var(--purple)); }
.mastery-value { font-family: Georgia, serif; font-size: 15px; text-align: right; }
.mastery-value.level-strong { color: var(--green); }
.mastery-value.level-growning, .mastery-value.level-growing { color: var(--purple); }
.mastery-value.level-weak { color: var(--rose); }
.mastery-value.level-empty { color: #aaa4b3; }
.activity-log ol { display: grid; gap: 0; padding: 0; margin: 0; list-style: none; }
.activity-log li { position: relative; display: grid; gap: 2px; padding: 9px 0 9px 17px; border-left: 1px solid #ddd6e7; }
.activity-log li::before { position: absolute; left: -4px; top: 16px; width: 7px; height: 7px; content: ""; border-radius: 50%; background: var(--green); }
.activity-log li span { font-size: 11px; }
.activity-log li time { color: var(--muted); font-size: 9px; }
.empty-log { padding: 25px 8px; color: var(--muted); text-align: center; }
.empty-log strong { color: var(--ink); font-size: 13px; }
.empty-log p { margin: 5px 0 0; font-size: 11px; }

.ai-fab { position: fixed; z-index: 25; right: 24px; bottom: 22px; display: flex; align-items: center; gap: 9px; padding: 12px 16px; border: 1px solid #d8d0e5; border-radius: 99px; background: white; box-shadow: 0 14px 40px rgba(48,37,72,.18); cursor: pointer; font-weight: 700; }
.ai-dot { width: 9px; height: 9px; border-radius: 50%; background: var(--green); box-shadow: 0 0 0 5px var(--green-soft); }
.ai-panel { position: fixed; z-index: 30; top: 0; right: 0; display: flex; width: min(420px, 100vw); height: 100vh; flex-direction: column; border-left: 1px solid var(--line); background: #fbfafd; box-shadow: -20px 0 55px rgba(45,35,67,.14); transform: translateX(102%); transition: transform .25s ease; }
.ai-panel.open { transform: translateX(0); }
.ai-panel header { display: flex; align-items: center; justify-content: space-between; padding: 18px; border-bottom: 1px solid var(--line); background: white; }
.ai-panel header > div { display: flex; align-items: center; gap: 11px; }
.ai-panel header strong, .ai-panel header small { display: block; }
.ai-panel header small { color: var(--muted); font-size: 10px; }
.ai-avatar { display: grid; width: 39px; height: 39px; place-items: center; border-radius: 12px; color: white; background: var(--purple); font-family: Georgia, serif; font-size: 20px; }
.icon-button { width: 36px; height: 36px; border: 0; border-radius: 10px; background: #f2eff6; cursor: pointer; font-size: 22px; }
.quick-actions { display: flex; gap: 7px; padding: 12px 14px; overflow-x: auto; border-bottom: 1px solid var(--line); }
.quick-actions button { flex: 0 0 auto; padding: 7px 10px; border: 1px solid #ddd6e7; border-radius: 99px; background: white; cursor: pointer; font-size: 11px; }
.quick-actions button:hover { color: var(--purple); border-color: #ac9fc5; }
.chat { flex: 1; padding: 17px; overflow-y: auto; }
.message { width: fit-content; max-width: 88%; padding: 11px 13px; margin-bottom: 11px; border-radius: 14px; white-space: pre-wrap; font-size: 13px; }
.message.assistant { border-bottom-left-radius: 4px; background: var(--purple-soft); }
.message.user { margin-left: auto; border-bottom-right-radius: 4px; color: white; background: var(--purple); }
.message.loading { color: var(--muted); animation: pulse 1s ease-in-out infinite; }
@keyframes pulse { 50% { opacity: .5; } }
.chat-form { display: grid; grid-template-columns: 1fr auto; gap: 9px; padding: 13px; border-top: 1px solid var(--line); background: white; }
.chat-form textarea { resize: none; min-height: 48px; padding: 11px; border: 1px solid #ddd6e7; border-radius: 12px; outline: none; }
.chat-form textarea:focus { border-color: var(--purple); box-shadow: 0 0 0 3px var(--purple-soft); }
.chat-form .primary-button { min-height: 48px; padding: 0 15px; }

.toast { position: fixed; z-index: 50; left: 50%; bottom: 24px; padding: 10px 16px; border-radius: 12px; color: white; background: #29263a; opacity: 0; pointer-events: none; transform: translate(-50%, 15px); transition: .2s ease; font-size: 12px; }
.toast.show { opacity: 1; transform: translate(-50%,0); }

.empty-state { padding: 60px 20px; color: var(--muted); text-align: center; }

.name-gate { position: fixed; z-index: 100; inset: 0; display: grid; place-items: center; padding: 20px; background: radial-gradient(circle at 75% 15%, rgba(141,214,189,.18), transparent 22rem), rgba(38,32,64,.94); backdrop-filter: blur(10px); }
.name-gate.hidden { display: none; }
.name-card { width: min(560px, 100%); padding: clamp(28px, 6vw, 48px); border: 1px solid rgba(255,255,255,.25); border-radius: 28px; background: var(--surface); box-shadow: 0 28px 90px rgba(0,0,0,.28); }
.name-mark { display: grid; width: 52px; height: 52px; place-items: center; margin-bottom: 22px; border-radius: 16px; color: white; background: linear-gradient(135deg, var(--green), var(--purple)); font-family: Georgia, serif; font-size: 27px; }
.name-card h1 { margin: 9px 0 10px; font-family: Georgia, "Songti SC", serif; font-size: clamp(29px, 5vw, 40px); line-height: 1.2; }
.name-card > p { margin: 0 0 22px; color: var(--muted); font-size: 13px; }
.name-card label { display: block; margin-bottom: 7px; font-size: 12px; font-weight: 700; }
.name-input-row { display: grid; grid-template-columns: 1fr auto; gap: 9px; }
.name-input-row input { min-width: 0; height: 48px; padding: 0 14px; border: 1px solid #d9d2e3; border-radius: 13px; outline: none; }
.name-input-row input:focus { border-color: var(--purple); box-shadow: 0 0 0 3px var(--purple-soft); }
.name-error { min-height: 22px; padding-top: 5px; color: var(--rose); font-size: 11px; }
.name-card > small { display: block; color: var(--muted); font-size: 10px; }

@media (max-width: 1020px) {
  .sidebar { position: static; width: 100%; max-height: none; padding: 16px 20px; }
  .brand { padding-bottom: 10px; }
  .today-card, .unit-nav, .sidebar-footer { display: none; }
  .coach-link { position: absolute; top: 18px; right: 20px; width: auto; margin: 0; }
  .coach-link small { display: none; }
  .main { margin-left: 0; padding-top: 28px; }
  .hero { grid-template-columns: 1fr; }
  .hero-visual { min-height: 250px; }
  .lesson-layout { grid-template-columns: 1fr; }
  .lesson-toc { display: none; }
  .coach-stats { grid-template-columns: repeat(2, 1fr); }
  .coach-grid { grid-template-columns: 1fr; }
}

@media (max-width: 680px) {
  .main { padding: 22px 16px 90px; }
  .hero-copy { padding: 28px 22px; }
  .hero h1 { font-size: 36px; }
  .stats, .unit-grid, .chapter-grid { grid-template-columns: 1fr; }
  .hero-visual { display: none; }
  .section-heading { align-items: start; flex-direction: column; gap: 3px; }
  .resume-card, .lesson-header { align-items: stretch; grid-template-columns: 1fr; flex-direction: column; }
  .vector-lab { grid-template-columns: 1fr; }
  .choices { grid-template-columns: 1fr; }
  .lesson-row { grid-template-columns: 40px 1fr; }
  .lesson-state { grid-column: 2; }
  .ai-fab { right: 14px; bottom: 14px; }
  .coach-link { top: 17px; right: 14px; padding: 8px; }
  .coach-link > span:last-child { display: none; }
  .coach-hero { grid-template-columns: 1fr; }
  .coach-today { min-width: 0; text-align: left; }
  .coach-stats { grid-template-columns: 1fr 1fr; }
  .coach-ai-card { grid-template-columns: 1fr; }
  .coach-ai-card .primary-button { width: 100%; }
  .coach-ai-result { grid-column: auto; }
  .mastery-row { grid-template-columns: minmax(130px, 1fr) 62px; }
  .mastery-bar { display: none; }
  .coach-banner { grid-template-columns: auto 1fr; }
  .coach-banner-arrow { display: none; }
  .chapter-page-head { grid-template-columns: 1fr; }
  .chapter-page-progress { text-align: left; }
  .name-input-row { grid-template-columns: 1fr; }
  .name-input-row .primary-button { width: 100%; }
}

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { scroll-behavior: auto !important; transition: none !important; animation: none !important; }
}