:root {
  --bg: #f6f8fb;
  --surface: #ffffff;
  --surface-2: #eef2f6;
  --text: #17212b;
  --muted: #647383;
  --line: #dce3ea;
  --accent: #1769ff;
  --accent-2: #0f52c9;
  --success: #087a4a;
  --warning: #9b6500;
  --danger: #b42318;
  --shadow: 0 6px 24px rgba(22, 34, 48, .08);
  --radius: 16px;
  --focus: 0 0 0 3px rgba(23, 105, 255, .2);
}

* { box-sizing: border-box; }
body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font: 15px/1.55 system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
}
button, input, textarea, select { font: inherit; }
button, a { -webkit-tap-highlight-color: transparent; }
a { color: inherit; }
button:focus-visible, a:focus-visible, input:focus-visible, textarea:focus-visible, select:focus-visible { outline: none; box-shadow: var(--focus); }

.skip-link {
  position: fixed; left: 16px; top: -60px; z-index: 1000; background: var(--text); color: white;
  padding: 10px 14px; border-radius: 10px; text-decoration: none;
}
.skip-link:focus { top: 14px; }

.topbar {
  position: sticky; top: 0; z-index: 50; display: grid; grid-template-columns: auto 1fr auto; gap: 18px;
  align-items: center; min-height: 68px; padding: 10px 18px; background: rgba(255,255,255,.94);
  border-bottom: 1px solid var(--line); backdrop-filter: blur(16px);
}
.brand-wrap { display:flex; align-items:center; gap:10px; min-width: max-content; }
.brand { border: 0; background: none; padding: 0; color: var(--text); font-weight: 800; font-size: 19px; cursor: pointer; display:inline-flex; align-items:center; gap:9px; min-width:0; }
.brand-mark { width:34px; height:34px; flex:none; border-radius:9px; }
.brand-text { white-space:nowrap; }
.brand-text span { font-weight: 500; color: var(--muted); }
.brand-badge { font-size: 10px; letter-spacing: .12em; color: var(--muted); padding: 4px 7px; border:1px solid var(--line); border-radius: 999px; }
.primary-nav { display:flex; align-items:center; gap: 6px; overflow:auto; scrollbar-width: thin; }
.primary-nav a { text-decoration:none; color:var(--muted); font-weight:600; padding:8px 9px; border-radius:10px; white-space:nowrap; }
.primary-nav a:hover, .primary-nav a[aria-current="page"] { color:var(--text); background:var(--surface-2); }
.top-actions { display:flex; align-items:center; gap:8px; white-space:nowrap; }
.pill { background: var(--surface-2); border:1px solid var(--line); padding: 7px 10px; border-radius:999px; font-size:12px; font-weight:700; }
.icon-button { width:36px; height:36px; display:grid; place-items:center; text-decoration:none; border:1px solid var(--line); border-radius:10px; background:var(--surface); }

main { max-width: 1240px; margin: 0 auto; padding: 28px 18px 56px; min-height: calc(100vh - 122px); }
.site-footer { border-top:1px solid var(--line); display:flex; justify-content:space-between; gap:20px; padding:18px; color:var(--muted); font-size:12px; background:var(--surface); }

.hero { display:grid; grid-template-columns: 1.6fr 1fr; gap:20px; align-items:stretch; }
.hero-card, .panel, .card { background:var(--surface); border:1px solid var(--line); border-radius:var(--radius); box-shadow:var(--shadow); }
.hero-card { padding:28px; }
.hero-card h1 { margin:0 0 10px; font-size:clamp(30px,4vw,46px); letter-spacing:-.03em; }
.hero-card p { color:var(--muted); max-width: 65ch; }
.hero-side { padding:22px; display:grid; gap:12px; align-content:center; }
.stat-grid { display:grid; grid-template-columns:repeat(2,1fr); gap:10px; }
.stat { padding:14px; background:var(--surface-2); border-radius:12px; }
.stat strong { display:block; font-size:24px; }
.stat span { color:var(--muted); font-size:12px; }

.row { display:flex; align-items:center; justify-content:space-between; gap:12px; flex-wrap:wrap; }
.row-start { display:flex; align-items:center; gap:10px; flex-wrap:wrap; }
.muted { color:var(--muted); }
.section-title { margin: 28px 0 12px; }
.section-title h2, .section-title h3 { margin:0; }
.section-title p { margin:3px 0 0; color:var(--muted); }
.button { display:inline-flex; align-items:center; justify-content:center; gap:7px; border:1px solid var(--line); border-radius:10px; padding:10px 14px; background:var(--surface); color:var(--text); font-weight:700; text-decoration:none; cursor:pointer; }
.button:hover { background:var(--surface-2); }
.button-primary { background:var(--accent); color:#fff; border-color:var(--accent); }
.button-primary:hover { background:var(--accent-2); }
.button-secondary { background:var(--surface-2); }
.button-danger { color:var(--danger); }
.button-small { padding:7px 10px; font-size:12px; }

.progress { height:8px; background:var(--surface-2); border-radius:999px; overflow:hidden; }
.progress > span { display:block; height:100%; width:0; background:var(--accent); border-radius:inherit; transition:width .25s ease; }

.grid { display:grid; gap:14px; }
.grid-2 { grid-template-columns:repeat(2,minmax(0,1fr)); }
.grid-3 { grid-template-columns:repeat(3,minmax(0,1fr)); }
.grid-4 { grid-template-columns:repeat(4,minmax(0,1fr)); }
.course-card { padding:18px; display:grid; gap:12px; }
.course-card h3 { margin:0; font-size:18px; }
.course-card .meta { font-size:12px; color:var(--muted); }
.course-card .num { color:var(--accent); font-weight:800; letter-spacing:.08em; }
.course-card .description { color:var(--muted); min-height:48px; }

.search-box { display:grid; grid-template-columns:1fr auto; gap:8px; }
input, textarea, select { width:100%; padding:11px 12px; border:1px solid var(--line); background:var(--surface); color:var(--text); border-radius:10px; }
textarea { min-height:120px; resize:vertical; }
label { display:grid; gap:6px; font-weight:700; }
label small { color:var(--muted); font-weight:500; }

.breadcrumbs { display:flex; gap:7px; align-items:center; color:var(--muted); font-size:12px; margin-bottom:16px; }
.lesson-layout { display:grid; grid-template-columns:minmax(0,1fr) 300px; gap:20px; align-items:start; }
.lesson-panel { padding:28px; }
.lesson-aside { position:sticky; top:90px; padding:18px; }
.lesson-panel h1 { margin-top:0; font-size:clamp(28px,4vw,40px); line-height:1.08; }
.lesson-content h2 { margin:30px 0 9px; font-size:22px; }
.lesson-content h3 { margin:20px 0 7px; font-size:17px; }
.lesson-content p { max-width:78ch; }
.lesson-content ul { padding-left: 21px; }
.reading-span { border-radius:4px; transition:background .12s ease; }
.reading-span.active-reading { background:#fff1a8; color:#111; box-shadow:0 0 0 2px #ffd95b; }
.reader-controls { display:grid; gap:9px; padding:14px; background:var(--surface-2); border-radius:12px; }
.reader-controls .control-row { display:flex; flex-wrap:wrap; gap:7px; }
.reader-status { font-size:12px; color:var(--muted); }

.quiz { display:grid; gap:14px; margin-top:18px; }
.quiz-question { padding:15px; border:1px solid var(--line); border-radius:12px; }
.quiz-question legend { font-weight:800; margin-bottom:8px; }
.option-list { display:grid; gap:7px; margin-top:10px; }
.option { display:flex; align-items:flex-start; gap:8px; padding:9px; border-radius:10px; }
.option:hover { background:var(--surface-2); }
.quiz-result { padding:15px; border-radius:12px; background:var(--surface-2); }

.brain-wrap { display:grid; grid-template-columns:1.2fr .9fr; gap:18px; }
.brain-canvas { background:#0c1118; border-radius:var(--radius); border:1px solid #1f2937; min-height:570px; padding:18px; }
.brain-svg { width:100%; height:520px; display:block; }
.brain-region { cursor:pointer; stroke:#dfe8f4; stroke-width:2; opacity:.84; transition:opacity .15s ease, transform .15s ease; transform-box:fill-box; transform-origin:center; }
.brain-region:hover, .brain-region.selected { opacity:1; stroke:#fff; stroke-width:3; }
.brain-label { fill:#fff; font-size:12px; font-weight:700; pointer-events:none; }
.structure-panel { padding:20px; }
.structure-panel h2 { margin:0 0 6px; }
.structure-panel .fact { padding:10px 0; border-bottom:1px solid var(--line); }
.structure-panel .fact:last-child { border-bottom:0; }

.lab-grid { display:grid; grid-template-columns:repeat(2,minmax(0,1fr)); gap:16px; }
.lab-card { padding:18px; }
.lab-output { margin-top:12px; padding:14px; background:#0c1118; color:#e7eef7; border-radius:12px; min-height:170px; }
canvas.lab-canvas { width:100%; height:170px; display:block; background:#0b0f14; border-radius:10px; }
.range { width:100%; }

.note-card, .achievement-card, .case-card { padding:16px; }
.badge { display:inline-flex; width:max-content; padding:4px 8px; border-radius:999px; background:var(--surface-2); color:var(--muted); font-size:11px; font-weight:700; }
.badge-success { color:var(--success); background:#e7f7ef; }
.badge-warning { color:var(--warning); background:#fff5d8; }

.auth-shell { max-width:520px; margin:35px auto; }
.auth-panel { padding:26px; }
.auth-panel h1 { margin-top:0; }
.form-grid { display:grid; gap:12px; }
.auth-error { color:var(--danger); background:#fff0ef; padding:10px; border-radius:10px; }

.empty { padding:32px; text-align:center; color:var(--muted); border:1px dashed var(--line); border-radius:14px; }
.loading { display:grid; place-items:center; min-height:280px; color:var(--muted); }
.error-panel { padding:25px; border:1px solid #f1c4c0; background:#fff7f6; border-radius:14px; }

.modal-backdrop { position:fixed; inset:0; display:grid; place-items:center; padding:20px; background:rgba(9,14,20,.55); z-index:100; }
.modal { width:min(680px,100%); max-height:90vh; overflow:auto; background:var(--surface); border-radius:18px; border:1px solid var(--line); box-shadow:0 20px 80px rgba(0,0,0,.2); }
.modal-head { padding:18px 20px; display:flex; justify-content:space-between; gap:10px; border-bottom:1px solid var(--line); }
.modal-body { padding:20px; }


.dark {
  --bg:#0b0f14; --surface:#111820; --surface-2:#18212c; --text:#e8eef4; --muted:#a6b4c3; --line:#273341; --accent:#6ea2ff; --accent-2:#87b1ff; --shadow:0 8px 30px rgba(0,0,0,.18);
}
.dark .topbar { background:rgba(17,24,32,.94); }
.dark .site-footer { background:var(--surface); }
.dark .button-primary { color:#07111e; }
.dark .active-reading { color:#121212; }

@media (max-width: 1080px) {
  .topbar { grid-template-columns: auto 1fr auto; }
  .primary-nav { order:3; grid-column:1 / -1; }
  .lesson-layout, .brain-wrap { grid-template-columns:1fr; }
  .lesson-aside { position:static; }
  .hero { grid-template-columns:1fr; }
  .lab-grid { grid-template-columns:1fr; }
}
@media (max-width: 760px) {
  main { padding:20px 12px 42px; }
  .topbar { padding:10px 12px; gap:9px; }
  .brand-badge, .pill { display:none; }
  .primary-nav a { padding:7px 8px; }
  .top-actions .icon-button { display:none; }
  .grid-2, .grid-3, .grid-4 { grid-template-columns:1fr; }
  .stat-grid { grid-template-columns:1fr 1fr; }
  .lesson-panel { padding:18px; }
  .brain-canvas { min-height:auto; padding:8px; }
  .brain-svg { height:400px; }
  .site-footer { flex-direction:column; }
  .search-box { grid-template-columns:1fr; }
}
@media (prefers-reduced-motion: reduce) {
  * { transition-duration:0.001ms !important; animation-duration:0.001ms !important; }
}

.curriculum-tools{display:flex;gap:14px;align-items:center;margin-top:20px;flex-wrap:wrap}
.curriculum-tools .search-field{flex:1;min-width:240px}
.curriculum-tools input{width:100%;padding:11px 13px;border:1px solid var(--border);border-radius:10px;background:var(--surface);color:var(--text);font:inherit}
.curriculum-list{display:grid;gap:12px;margin-top:18px}
.curriculum-course{border:1px solid var(--border);border-radius:14px;background:var(--surface);overflow:hidden}
.curriculum-course[hidden]{display:none}
.curriculum-course>summary{list-style:none;cursor:pointer;display:flex;align-items:center;justify-content:space-between;gap:16px;padding:17px 18px}
.curriculum-course>summary::-webkit-details-marker{display:none}
.curriculum-course>summary:hover{background:color-mix(in srgb,var(--surface) 94%,var(--accent) 6%)}
.curriculum-course-main{display:flex;gap:14px;align-items:flex-start;min-width:0}
.curriculum-course-main>div{min-width:0}
.curriculum-course-main strong{display:block;font-size:1.04rem;margin-bottom:4px}
.curriculum-course-main .muted{max-width:760px}
.curriculum-course-meta{display:flex;gap:10px;align-items:center;white-space:nowrap}
.curriculum-lessons{border-top:1px solid var(--border);padding:8px}
.curriculum-lesson{display:grid;grid-template-columns:42px minmax(0,1fr) auto;gap:12px;align-items:start;padding:13px 10px;border-radius:10px;color:inherit;text-decoration:none}
.curriculum-lesson:hover{background:var(--surface-2)}
.curriculum-lesson-number{font-weight:700;color:var(--accent);padding-top:3px}
.curriculum-lesson-body strong{display:block}
.curriculum-lesson-body p{margin:5px 0;color:var(--muted);line-height:1.48}
@media(max-width:720px){.curriculum-course>summary{align-items:flex-start}.curriculum-course-meta{flex-direction:column;align-items:flex-end;gap:5px}.curriculum-lesson{grid-template-columns:32px minmax(0,1fr);}.curriculum-lesson>.button{grid-column:2;justify-self:start}}

.lesson-card-summary{margin:7px 0 10px;color:var(--muted);line-height:1.48}

.noscript-panel { max-width:760px; margin:60px auto; padding:28px; border:1px solid var(--line); border-radius:16px; background:var(--surface); }
.brand:focus-visible, .brand-mark:focus-visible { outline:3px solid var(--accent); outline-offset:3px; }