:root {
  --bg: #f7f4ee;
  --panel: #fffaf2;
  --panel-strong: #fff4df;
  --text: #251a12;
  --muted: #7c6d5c;
  --line: #eadbc6;
  --accent: #b45f06;
  --accent-2: #2563eb;
  --green: #15803d;
  --purple: #7e22ce;
  --shadow: 0 18px 45px rgba(74,45,15,.10);
  --sidebar-w: 300px;
  --z-content: 0;
  --z-bottom-nav: 3000;
  --z-overlay: 4000;
  --z-sidebar: 5000;
  --z-toast: 6000;
}

* { box-sizing: border-box; }

body {
  margin: 0;
  font-family: "Microsoft YaHei","PingFang SC",system-ui,-apple-system,BlinkMacSystemFont,sans-serif;
  background: radial-gradient(circle at top left,#fff7df 0,var(--bg) 36rem);
  color: var(--text);
  padding-bottom: 60px; /* room for bottom nav on mobile */
}

/* ── layout ── */
.app-shell {
  display: grid;
  grid-template-columns: var(--sidebar-w) minmax(0,1fr);
  min-height: 100vh;
  position: relative;
  z-index: var(--z-content);
  isolation: isolate;
}

/* ── sidebar ── */
.sidebar {
  position: sticky; top: 0; height: 100vh; overflow-y: auto;
  padding: 18px 14px; border-right: 1px solid var(--line);
  background: rgba(255,250,242,.95); backdrop-filter: blur(12px);
  display: flex; flex-direction: column; gap: 12px;
}

.sidebar-overlay {
  display: none; position: fixed; inset: 0;
  background: rgba(0,0,0,.42); z-index: var(--z-overlay);
  backdrop-filter: blur(2px);
}
.sidebar-overlay.active,
.sidebar-overlay.open { display: block; }

.sidebar-close { display: none; }

.brand {
  display: flex; gap: 10px; align-items: center;
}
.brand-mark {
  width: 44px; height: 44px; display: grid; place-items: center;
  border-radius: 14px; color: #fff; flex-shrink: 0;
  background: linear-gradient(135deg,var(--accent),#f59e0b);
  font-size: 26px; font-weight: 900; box-shadow: var(--shadow);
}
h1,h2,h3,p { margin-top: 0; }
.brand h1 { margin: 0 0 3px; font-size: 16px; }
.brand p  { margin: 0; color: var(--muted); font-size: 11px; }

/* ── dashboard card ── */
.dashboard-card {
  padding: 10px 12px; border-radius: 14px;
  background: var(--panel-strong); border: 1px solid var(--line);
}
.dash-stats {
  display: grid; grid-template-columns: repeat(3,1fr); gap: 6px;
  margin-bottom: 8px; text-align: center;
}
.dash-stat-item { font-size: 11px; }
.dash-stat-item strong { display: block; font-size: 18px; }
.dash-stat-item.unseen  strong { color: #b91c1c; }
.dash-stat-item.familiar strong { color: #1d4ed8; }
.dash-stat-item.known   strong { color: var(--green); }

.dash-progress-bar {
  height: 6px; border-radius: 99px; background: #e9ddd0; overflow: hidden;
}
.dash-fill {
  height: 100%; border-radius: 99px;
  background: linear-gradient(90deg,var(--accent),var(--green));
  transition: width .4s ease;
}
.dash-hint { margin: 6px 0 0; font-size: 11px; color: var(--muted); text-align: center; }
.privacy-reset-btn {
  width: 100%; margin-top: -2px; padding: 8px 10px;
  border-radius: 12px; border: 1px dashed #e3b58f;
  background: #fffaf5; color: #9a3412;
  font-size: 12px; font-weight: 700; cursor: pointer;
  transition: background .15s, border-color .15s, transform .15s;
}
.privacy-reset-btn:hover, .privacy-reset-btn:focus-visible {
  background: #ffedd5; border-color: #fb923c; transform: translateY(-1px);
}

/* ── quick nav ── */
.quick-nav {
  display: grid; grid-template-columns: 1fr 1fr; gap: 6px;
}
.qnav-btn {
  padding: 8px 6px; border-radius: 10px; font-size: 12px; font-weight: 700;
  border: 1px solid var(--line); background: white; color: var(--muted);
  cursor: pointer; transition: all .15s;
}
.qnav-btn:hover, .qnav-btn.active {
  background: var(--panel-strong); color: var(--accent); border-color: var(--accent);
}

/* ── chapter nav ── */
.chapter-nav {
  display: flex; flex-direction: column; gap: 10px;
  flex: 1 1 auto; min-height: 0; overflow-y: auto;
  padding-bottom: 8px; overscroll-behavior: contain;
}
.nav-group {
  border: 1px solid var(--line); border-radius: 14px;
  background: #fffdf8; overflow: hidden;
  flex: 0 0 auto;
}
.nav-group h2 {
  margin: 0; padding: 10px 12px; font-size: 13px;
  background: var(--panel-strong);
}
.nav-group button {
  width: 100%; border: 0; background: transparent;
  padding: 8px 12px; text-align: left; cursor: pointer;
  color: var(--text); border-top: 1px solid #f4eadb; font-size: 12px;
}
.nav-group button:hover, .nav-group button.active {
  background: #fff2d7; color: var(--accent);
}

/* ── nav progress dot ── */
.nav-group button { display: flex; justify-content: space-between; align-items: center; }
.nav-dot {
  width: 7px; height: 7px; border-radius: 50%; flex-shrink: 0; margin-left: 5px;
}
.nav-dot.dot-none    { background: #ef4444; }   /* 全未掌握必背卡 */
.nav-dot.dot-partial { background: #f59e0b; }   /* 部分掌握 */
.nav-dot.dot-done    { background: #86efac; }   /* 必背全掌握 */

/* ── main ── */
.main { padding: 24px; max-width: 1280px; }

/* ── hero ── */
.hero {
  display: grid; grid-template-columns: 1fr auto;
  gap: 16px; align-items: center; margin-bottom: 18px;
  padding: 22px 24px; border-radius: 22px;
  background: rgba(255,250,242,.92); border: 1px solid var(--line);
  box-shadow: var(--shadow);
}
.eyebrow { color: var(--accent); font-weight: 800; letter-spacing: .08em; font-size: 12px; margin-bottom: 6px; }
.hero-text-block h2 { font-size: clamp(18px,2.5vw,32px); line-height: 1.2; margin-bottom: 8px; }
.hero-sub { color: var(--muted); line-height: 1.7; font-size: 13px; margin: 0; }
.hero-stats-row { display: flex; gap: 12px; }
.hero-stat {
  display: grid; place-items: center; text-align: center;
  min-width: 58px; padding: 10px 8px; border-radius: 14px;
  background: var(--panel-strong); border: 1px solid var(--line);
}
.hero-stat strong { font-size: 22px; color: var(--accent); line-height: 1; }
.hero-stat span { font-size: 11px; color: var(--muted); font-weight: 700; }

/* ── toolbar ── */
.toolbar {
  display: flex; gap: 10px; align-items: end; flex-wrap: wrap;
  padding: 14px; margin-bottom: 8px; border-radius: 18px;
  background: rgba(255,250,242,.9); border: 1px solid var(--line);
  box-shadow: var(--shadow);
}
.toolbar label { display: grid; gap: 4px; font-size: 12px; color: var(--muted); }
.search-box { flex: 1 1 260px; }
.toolbar-right { display: flex; gap: 6px; align-items: flex-end; flex-wrap: wrap; margin-left: auto; }

input, select {
  min-height: 38px; border: 1px solid var(--line);
  border-radius: 10px; padding: 0 10px; font: inherit;
  background: white; color: var(--text);
}
button {
  cursor: pointer; min-height: 38px; border-radius: 10px;
  padding: 0 12px; font: inherit; font-weight: 700;
  background: var(--accent); color: white; border: 1px solid var(--accent);
}
.btn-ghost {
  background: white; color: var(--muted); border-color: var(--line);
  font-weight: 600; font-size: 12px;
}
.btn-ghost:hover { background: var(--panel-strong); color: var(--accent); }
.btn-ghost.active-mode { background: #dcfce7; color: var(--green); border-color: #86efac; }
.btn-primary { background: var(--accent); color: white; }

/* ── keyboard hint ── */
.keyboard-hint {
  font-size: 11px; color: var(--muted); margin-bottom: 8px; padding: 6px 10px;
}
kbd {
  display: inline-block; padding: 2px 5px; border-radius: 5px;
  border: 1px solid var(--line); background: white;
  font-size: 10px; font-family: monospace; color: var(--text); margin: 0 2px;
}

/* ── results info ── */
.results-info { color: var(--muted); margin: 6px 4px 10px; font-size: 12px; }

/* ── view sections ── */
.view-section { }
.hidden { display: none !important; }

/* ── formula list ── */
.formula-list { display: grid; gap: 14px; }

/* ── formula card ── */
.formula-card {
  padding: 18px; border-radius: 20px;
  background: rgba(255,250,242,.92); border: 1px solid var(--line);
  box-shadow: var(--shadow); transition: outline .1s;
  scroll-margin-top: 16px;
}
.formula-card.kb-focus {
  outline: 3px solid var(--accent-2); outline-offset: 2px;
}

.formula-head {
  display: flex; gap: 12px; justify-content: space-between; align-items: start;
}
.formula-title { display: flex; align-items: center; gap: 8px; flex-wrap: wrap; }
.formula-title h3 { margin: 0; font-size: 18px; }

/* search highlight */
.highlight { background: #fef08a; border-radius: 3px; }

/* ── badges ── */
.badge {
  display: inline-flex; align-items: center; border-radius: 999px;
  padding: 3px 8px; font-size: 11px; font-weight: 800;
  background: #fef3c7; color: #92400e;
}
.badge.必背 { background: #fee2e2; color: #b91c1c; }
.badge.常用 { background: #dbeafe; color: #1d4ed8; }
.badge.技巧 { background: #dcfce7; color: var(--green); }
.badge.了解 { background: #ede9fe; color: #6d28d9; }
.badge.拓展 { background: #f3f4f6; color: #374151; }

/* ── card actions ── */
.card-actions { display: flex; gap: 6px; align-items: center; flex-shrink: 0; }

.mastery-btn {
  font-size: 11px; font-weight: 700; min-height: 28px; padding: 0 8px;
  border-radius: 8px; white-space: nowrap; cursor: pointer;
  background: #f3f4f6; color: #374151; border-color: #d1d5db;
}
.mastery-btn.m-new      { background: #fee2e2; color: #b91c1c; border-color: #fca5a5; }
.mastery-btn.m-familiar { background: #dbeafe; color: #1d4ed8; border-color: #93c5fd; }
.mastery-btn.m-known    { background: #dcfce7; color: var(--green); border-color: #86efac; }

.fav-btn {
  font-size: 16px; min-height: 28px; padding: 0 6px;
  border-radius: 8px; background: white; border-color: var(--line);
  color: var(--muted); line-height: 1;
}
.fav-btn.active { color: #f59e0b; border-color: #f59e0b; background: #fffbeb; }

.chapter-line { margin: 6px 0 0; color: var(--muted); font-size: 12px; }

/* ── formula block ── */
.formula {
  margin: 14px 0; padding: 12px 14px; overflow-x: auto;
  border-radius: 14px; background: #fff8e8; border: 1px solid #f1dfbd;
  -webkit-overflow-scrolling: touch;
  position: relative;
  z-index: 0;
  isolation: isolate;
}
.formula mjx-container { max-width: none !important; position: relative; z-index: 0; }
.math-warning {
  margin-top: 8px; padding: 6px 10px; border-radius: 8px;
  background: #fee2e2; color: #991b1b; font-size: 12px; font-weight: 700;
}

/* ── flash mode ── */
.flash-body { position: relative; }
.formula-card .flash-cover {
  position: absolute; inset: 0;
  background: rgba(255,248,232,.97); border-radius: 12px;
  display: flex; align-items: center; justify-content: center;
  cursor: pointer; z-index: 2;
  font-weight: 700; color: var(--accent);
  border: 2px dashed var(--line); font-size: 14px;
}
.formula-card.flash-revealed .flash-cover { display: none; }
.flash-mode .formula-card:not(.flash-revealed) .flash-content {
  visibility: hidden; user-select: none; pointer-events: none;
}

/* ── intuition, tags ── */
.intuition { margin: 0 0 8px; line-height: 1.75; color: #4c3824; font-size: 14px; }
.tag-row { display: flex; gap: 6px; flex-wrap: wrap; }
.tag {
  border: 1px solid var(--line); color: var(--muted);
  border-radius: 999px; padding: 2px 7px; font-size: 11px; background: #fffdf8;
}

/* ── details / detail grid ── */
details { margin-top: 12px; border-top: 1px dashed var(--line); padding-top: 10px; }
summary { cursor: pointer; color: var(--accent); font-weight: 800; font-size: 13px; }
.detail-grid {
  display: grid; grid-template-columns: repeat(2,minmax(0,1fr));
  gap: 10px; margin-top: 12px;
}
.detail-block {
  padding: 12px; border-radius: 14px;
  background: #fffdf8; border: 1px solid #f0e2cf; line-height: 1.7;
}
.detail-block h4 { margin: 0 0 6px; color: var(--accent); font-size: 13px; }
.detail-block p  { margin: 0; color: #4b3b2b; font-size: 13px; }
.interactive { grid-column: 1/-1; background: #f8fbff; border-color: #d8e7ff; }
.demo-box { display: grid; gap: 8px; }
.demo-controls { display: flex; gap: 8px; align-items: center; flex-wrap: wrap; font-size: 13px; }
.demo-controls input[type="range"] { width: 200px; max-width: 100%; }
.demo-hint { font-size: 12px; color: #1d4ed8; margin: 0 0 4px; }
.demo-trigger { font-size: 12px; color: var(--green); margin: 0 0 4px; font-weight: 700; }
.demo-warn { font-size: 12px; color: #dc2626; margin: 4px 0 0; }
.demo-readout {
  font-family: Consolas,"Cascadia Mono",monospace; font-size: 12px;
  background: white; border: 1px solid #dbeafe;
  border-radius: 10px; padding: 8px; white-space: pre-wrap;
}
.code-panel { margin: 6px 0 0; background: #111827; border: 1px solid #1f2937; line-height: 1.6; }
svg.demo-svg { width: 100%; height: 240px; border-radius: 12px; background: white; border: 1px solid #dbeafe; }
code, pre { font-family: Consolas,"Cascadia Mono",monospace; }
pre { overflow: auto; padding: 10px; border-radius: 10px; background: #1f2937; color: #f8fafc; font-size: 12px; }

.empty-state {
  padding: 22px; border: 1px dashed var(--line);
  border-radius: 18px; color: var(--muted);
  background: rgba(255,250,242,.7); text-align: center;
}

/* ── labs grid ── */
.labs-header { margin-bottom: 16px; }
.labs-header h2 { font-size: 22px; margin-bottom: 4px; }
.labs-sub { color: var(--muted); font-size: 13px; margin: 0; }
.labs-grid { display: grid; grid-template-columns: repeat(auto-fill,minmax(280px,1fr)); gap: 14px; }
.lab-card {
  padding: 16px; border-radius: 18px;
  background: rgba(255,250,242,.92); border: 1px solid var(--line);
  box-shadow: var(--shadow); cursor: pointer;
  transition: transform .15s, box-shadow .15s;
}
.lab-card:hover { transform: translateY(-2px); box-shadow: 0 24px 50px rgba(74,45,15,.14); }
.lab-card-icon { font-size: 28px; margin-bottom: 6px; }
.lab-card h3 { margin: 0 0 4px; font-size: 15px; }
.lab-card .lab-trigger { font-size: 11px; color: var(--green); font-weight: 700; margin: 4px 0; }
.lab-card .lab-desc { font-size: 12px; color: var(--muted); margin: 0; }
.lab-card .lab-link-btn {
  margin-top: 10px; font-size: 11px; padding: 4px 10px;
  background: var(--panel-strong); color: var(--accent);
  border: 1px solid var(--accent); border-radius: 8px;
}

/* ── review ── */
.review-header { margin-bottom: 14px; }
.review-header h2 { font-size: 22px; margin-bottom: 4px; }
.review-sub { color: var(--muted); font-size: 13px; margin: 0 0 10px; }
.review-controls { display: flex; gap: 8px; }

/* ── errors ── */
.errors-header { margin-bottom: 14px; }
.errors-header h2 { font-size: 22px; margin-bottom: 4px; }
.errors-sub { color: var(--muted); font-size: 13px; margin: 0 0 10px; }
.error-tags { display: flex; flex-wrap: wrap; gap: 8px; }
.error-tag {
  padding: 7px 14px; border-radius: 999px; font-size: 13px;
  background: white; border: 1px solid var(--line); color: var(--muted);
  cursor: pointer; font-weight: 600;
}
.error-tag:hover, .error-tag.active {
  background: var(--panel-strong); color: var(--accent); border-color: var(--accent);
}

/* ── mastery stats ── */
.stat-unseen   { color: #b91c1c; font-weight: 700; }
.stat-familiar { color: #1d4ed8; font-weight: 700; }
.stat-known    { color: var(--green); font-weight: 700; }

/* ── bottom nav (mobile) ── */
.bottom-nav {
  display: none; position: fixed; bottom: 0; left: 0; right: 0;
  min-height: 58px; padding-bottom: env(safe-area-inset-bottom);
  background: rgba(255,250,242,.97);
  border-top: 1px solid var(--line); backdrop-filter: blur(12px);
  z-index: var(--z-bottom-nav); justify-content: space-around; align-items: center;
  isolation: isolate; transform: translateZ(0);
}
.bnav-btn {
  display: flex; flex-direction: column; align-items: center;
  gap: 2px; font-size: 20px; min-height: unset; padding: 4px 8px;
  background: transparent; border: none; color: var(--muted); border-radius: 10px;
}
.bnav-btn span { font-size: 10px; font-weight: 700; }
.bnav-btn.active { color: var(--accent); }

/* ── responsive ── */
@media (max-width: 860px) {
  .app-shell { grid-template-columns: 1fr; }
  .sidebar {
    position: fixed; top: 0; left: 0; bottom: 0; z-index: var(--z-sidebar);
    width: min(var(--sidebar-w), 85vw); transform: translateX(-110%);
    transition: transform .25s ease;
  }
  .sidebar.open { transform: translateX(0); }
  .sidebar-close { display: block; margin-left: auto; }
  .bottom-nav { display: flex; }
  .hero { grid-template-columns: 1fr; }
  .hero-stats-row { flex-wrap: wrap; }
  .detail-grid { grid-template-columns: 1fr; }
  .main { padding: 14px 14px calc(86px + env(safe-area-inset-bottom)); }
  .toolbar-right { margin-left: 0; width: 100%; }
  .labs-grid { grid-template-columns: 1fr; }
}

/* ══════════════════════════════════════════════════════════════
   Phase 3A — 教学化交互模块共用骨架
══════════════════════════════════════════════════════════════ */

/* lab-shell: 每个重构模块的外壳 */
.lab-shell {
  display: grid; gap: 10px;
  border: 1px solid #e2d8cc; border-radius: 16px;
  padding: 14px; background: #fffdf8;
}
.lab-header {
  display: flex; flex-direction: column; gap: 3px;
  border-bottom: 1px dashed var(--line); padding-bottom: 8px;
}
.lab-title { font-weight: 800; font-size: 14px; color: var(--accent); }
.lab-goal  { font-size: 12px; color: var(--muted); line-height: 1.5; }

/* ctrl row */
.lab-ctrl-row {
  display: flex; gap: 10px; align-items: center; flex-wrap: wrap;
}
.lab-ctrl-label {
  display: flex; flex-direction: column; gap: 2px;
  font-size: 12px; color: var(--muted); font-weight: 700;
}
.lab-ctrl-hint { font-size: 11px; color: #94a3b8; font-weight: 400; }
.lab-range { width: 180px; max-width: 100%; }
.lab-range-val { font-size: 13px; font-weight: 700; color: var(--text); min-width: 60px; }

/* insight bar at bottom */
.lab-insight {
  display: flex; flex-direction: column; gap: 4px;
  border-top: 1px dashed var(--line); padding-top: 8px; font-size: 12px;
}
.insight-trigger { color: var(--green); font-weight: 700; }
.insight-warn    { color: #dc2626; }
.insight-task    { color: #7c3aed; }

.mini-stat-grid {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 8px;
  margin: 8px 0;
}
.mini-stat-grid > div {
  border: 1px solid #e2e8f0;
  border-radius: 12px;
  padding: 8px 10px;
  background: #f8fafc;
}
.mini-stat-grid span {
  display: block;
  color: var(--muted);
  font-size: 11px;
}
.mini-stat-grid strong {
  display: block;
  color: var(--text);
  font-size: 14px;
  margin-top: 2px;
}
.tangent-readout p {
  margin: 8px 0 0;
  color: var(--muted);
  font-size: 12px;
  line-height: 1.6;
}
@media (max-width: 720px) { .mini-stat-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); } }
@media (max-width: 440px) { .mini-stat-grid { grid-template-columns: 1fr; } }

/* ── equivalent-compare ── */
.ec-svg { height: 120px; }
.ec-grid {
  display: grid; grid-template-columns: repeat(3, 1fr); gap: 8px;
}
.ec-zone {
  border-radius: 12px; padding: 8px 10px; font-size: 11px;
}
.ec-zone-eq   { background: #eff6ff; border: 1px solid #bfdbfe; }
.ec-zone-ord  { background: #fffbeb; border: 1px solid #fde68a; }
.ec-zone-trap { background: #fef2f2; border: 1px solid #fecaca; }
.ec-zone-title {
  font-weight: 800; font-size: 12px; margin-bottom: 6px; line-height: 1.4;
}
.ec-zone-eq   .ec-zone-title { color: #1d4ed8; }
.ec-zone-ord  .ec-zone-title { color: #b45309; }
.ec-zone-trap .ec-zone-title { color: #b91c1c; }
.ec-row { display: flex; flex-direction: column; gap: 1px; margin-bottom: 5px; }
.ec-row-label { font-size: 11px; color: var(--muted); }
.ec-row-val   { font-size: 11px; font-family: Consolas, monospace; color: var(--text); }
@media (max-width: 600px) { .ec-grid { grid-template-columns: 1fr; } }

/* ── taylor-order-lab ── */
.tol-tabs {
  display: flex; gap: 6px;
}
.tol-tab {
  padding: 5px 14px; border-radius: 999px; font-size: 12px;
  background: white; color: var(--muted); border: 1px solid var(--line);
  font-weight: 600; min-height: unset;
}
.tol-tab.active {
  background: var(--accent); color: white; border-color: var(--accent);
}
.tol-readout, .tol-combo-readout {
  border-radius: 10px; background: #f8fafc;
  border: 1px solid #e2e8f0; padding: 8px 10px;
}
.tol-readout-grid {
  display: grid; grid-template-columns: repeat(2, 1fr); gap: 6px;
}
.tol-readout-grid > div {
  display: flex; flex-direction: column; gap: 2px; font-size: 12px;
}
.tol-label { color: var(--muted); font-size: 11px; }
.tol-readout-grid code {
  font-size: 12px; color: var(--accent);
  background: #fff8e8; border-radius: 4px; padding: 1px 4px;
}
@media (max-width: 500px) { .tol-readout-grid { grid-template-columns: 1fr; } }

/* ── matrix-eigen-lab ── */
.mel-layout {
  display: grid; grid-template-columns: 200px 1fr; gap: 12px; align-items: start;
}
.mel-matrix-label { font-size: 12px; color: var(--muted); margin-bottom: 6px; font-weight: 700; }
.mel-matrix-grid  { display: grid; gap: 4px; margin-bottom: 10px; }
.mel-matrix-row   { display: flex; gap: 4px; }
.mel-inp {
  width: 60px; height: 36px; border-radius: 8px;
  border: 1px solid var(--line); text-align: center;
  font-size: 15px; font-weight: 700; color: var(--accent);
  background: white; padding: 0 4px;
}
.mel-svg { height: 280px; }
.mel-nums { display: grid; gap: 4px; }
.mel-num-row {
  display: flex; justify-content: space-between; align-items: center;
  font-size: 12px; padding: 3px 6px; border-radius: 6px;
  background: #f8fafc; border: 1px solid #e2e8f0;
}
.mel-num-row code { font-size: 12px; color: var(--accent); }
.mel-num-verdict { justify-content: center; font-weight: 800; margin-top: 2px; }
.mel-pos  { color: var(--green); }
.mel-semi { color: #b45309; }
.mel-neg  { color: #b91c1c; }
.mel-sylvester {
  margin-top: 8px; font-size: 11px;
  border: 1px solid var(--line); border-radius: 10px;
  overflow: hidden;
}
.mel-sylvester-title {
  background: var(--panel-strong); padding: 5px 8px;
  font-weight: 700; font-size: 11px; color: var(--accent);
}
.mel-sylvester-row {
  padding: 4px 8px; border-top: 1px solid var(--line);
}
.mel-sylvester-concl {
  padding: 5px 8px; border-top: 1px solid var(--line);
  font-weight: 700; background: #f8fafc;
}
.sy-ok   { background: #f0fdf4; color: #15803d; }
.sy-fail { background: #fef2f2; color: #b91c1c; }
@media (max-width: 600px) {
  .mel-layout { grid-template-columns: 1fr; }
  .mel-svg { height: 220px; }
}

/* ══════════════════════════════════════════════════════════════
   Phase 3B — trig / wallis / integral-picker / prob-distribution
══════════════════════════════════════════════════════════════ */

/* ── trig-transform-lab ── */
.ttl-shell {}
.ttl-mode-bar { display: flex; gap: 6px; flex-wrap: wrap; }
.ttl-mode-btn {
  padding: 5px 13px; border-radius: 999px; font-size: 12px; font-weight: 700;
  background: white; color: var(--muted); border: 1px solid var(--line);
  cursor: pointer; min-height: unset; transition: all .12s;
}
.ttl-mode-btn.active { background: var(--accent); color: white; border-color: var(--accent); }
.ttl-scene-bar {
  font-size: 12px; color: var(--green); font-weight: 600;
  padding: 5px 8px; background: #f0fdf4; border-radius: 8px; border: 1px solid #bbf7d0;
}
.ttl-ctrl-row { display: flex; gap: 16px; flex-wrap: wrap; align-items: flex-start; }
.ttl-ctrl-lbl {
  display: flex; flex-direction: column; gap: 3px;
  font-size: 12px; color: var(--muted); font-weight: 700;
}
.ttl-formula {
  font-size: 13px; font-weight: 700; color: var(--accent);
  background: #fff8e8; border: 1px solid #f1dfbd; border-radius: 10px;
  padding: 8px 12px; font-family: Consolas, monospace;
  overflow-x: auto; white-space: nowrap;
}
.ttl-insight { font-size: 12px; }

/* ── wallis-recursion ── */
.wal-shell {}
.wal-chain {
  display: flex; align-items: center; flex-wrap: wrap; gap: 4px;
  padding: 10px 12px; background: #f8fafc;
  border: 1px solid #e2e8f0; border-radius: 12px; min-height: 68px;
}
.wal-step {
  display: flex; flex-direction: column; align-items: center; gap: 2px;
  background: white; border: 1px solid var(--line); border-radius: 8px;
  padding: 5px 9px; min-width: 52px;
}
.wal-step-target {
  background: var(--panel-strong); border-color: var(--accent);
  box-shadow: 0 0 0 2px rgba(180,95,6,.18);
}
.wal-step-label { font-size: 12px; font-weight: 800; color: var(--accent); }
.wal-step-val   { font-size: 10px; color: var(--muted); font-family: Consolas, monospace; }
.wal-arrow  { font-size: 11px; color: var(--muted); display: flex; flex-direction: column; align-items: center; }
.wal-coef   { font-size: 10px; color: #7c3aed; font-weight: 700; white-space: nowrap; }
.wal-panels { display: grid; grid-template-columns: 1fr 1fr; gap: 10px; }
.wal-panel  {
  border-radius: 12px; padding: 10px 12px; font-size: 12px;
}
.wal-even { background: #eff6ff; border: 1px solid #bfdbfe; }
.wal-odd  { background: #fefce8; border: 1px solid #fef08a; }
.wal-panel-title { font-weight: 800; font-size: 13px; margin-bottom: 6px; }
.wal-even .wal-panel-title { color: #1d4ed8; }
.wal-odd  .wal-panel-title { color: #854d0e; }
.wal-panel-why { font-size: 11px; color: var(--muted); margin-top: 6px; }
.wal-fml-row {
  padding: 3px 0; border-bottom: 1px dashed #e2e8f0;
  font-family: Consolas, monospace; font-size: 11px;
}
.wal-fml-hi { background: rgba(180,95,6,.1); border-radius: 4px; padding: 2px 4px; font-weight: 700; }
.wal-fml-row code { color: var(--accent); font-size: 11px; }
@media (max-width: 560px) { .wal-panels { grid-template-columns: 1fr; } }

/* ── integral-method-picker ── */
.imp-shell {}
.imp-feature-bar {
  display: flex; flex-wrap: wrap; gap: 6px; align-items: center;
  padding: 8px 10px; background: #f8fafc; border-radius: 10px;
  border: 1px solid #e2e8f0;
}
.imp-feature-label { font-size: 12px; color: var(--muted); font-weight: 700; margin-right: 2px; }
.imp-tag {
  padding: 3px 10px; border-radius: 999px; font-size: 11px; font-weight: 600;
  background: white; color: var(--muted); border: 1px solid var(--line);
  cursor: pointer; min-height: unset; transition: all .12s;
}
.imp-tag:hover { background: var(--panel-strong); color: var(--accent); border-color: var(--accent); }
.imp-tag.imp-tag-active { background: var(--accent); color: white; border-color: var(--accent); }
.imp-clear { color: #ef4444; border-color: #fecaca; }
.imp-tree {
  display: flex; flex-direction: column; gap: 0;
  border: 1px solid var(--line); border-radius: 12px; overflow: hidden;
}
.imp-node {
  display: flex; align-items: center; gap: 10px;
  padding: 9px 14px; font-size: 13px; cursor: pointer;
  background: white; border-bottom: 1px solid var(--line);
  transition: background .1s;
}
.imp-node:last-child { border-bottom: none; }
.imp-node:hover { background: #fff8e8; }
.imp-node.imp-node-active { background: var(--panel-strong); font-weight: 700; }
.imp-node-icon  { font-size: 16px; flex-shrink: 0; }
.imp-node-label { flex: 1; }
.imp-node-arrow { color: var(--accent); font-weight: 800; }
.imp-connector  { height: 0; }
.imp-detail { min-height: 60px; }
.imp-detail-empty { padding: 16px; color: var(--muted); font-size: 13px; text-align: center; }
.imp-detail-card {
  padding: 12px 14px; border: 1px solid #dbeafe; border-radius: 12px;
  background: #f0f9ff; display: grid; gap: 6px;
}
.imp-detail-title { font-weight: 800; font-size: 14px; color: #1d4ed8; }
.imp-detail-why   { font-size: 12px; color: var(--text); }
.imp-detail-steps { font-size: 12px; }
.imp-detail-steps ol { margin: 4px 0 0 16px; padding: 0; }
.imp-detail-steps li { margin-bottom: 2px; }
.imp-detail-example { font-size: 12px; }
.imp-detail-example code {
  background: white; border: 1px solid #bfdbfe; border-radius: 4px;
  padding: 2px 6px; font-size: 12px; color: #1e40af;
}
.imp-detail-bad { font-size: 12px; color: #b91c1c; }

/* ── probability-distribution-lab ── */
.pdl-shell {}
.pdl-ctrl-row { display: flex; gap: 20px; flex-wrap: wrap; }
.pdl-svg { height: 230px; }
.pdl-stats {
  display: grid; grid-template-columns: repeat(4, 1fr); gap: 6px;
}
.pdl-stat {
  display: flex; flex-direction: column; gap: 2px; align-items: center;
  padding: 6px 4px; border-radius: 8px; background: #f8fafc;
  border: 1px solid #e2e8f0; font-size: 11px; color: var(--muted); text-align: center;
}
.pdl-stat strong { font-size: 15px; color: var(--text); }
.pdl-strict { border-color: #fca5a5; background: #fef2f2; }
.pdl-loose  { border-color: #bbf7d0; background: #f0fdf4; }
.pdl-beta   { border-color: #bfdbfe; background: #eff6ff; }
.pdl-power  { border-color: #bbf7d0; background: #f0fdf4; }
.pdl-good   { color: #15803d; }
.pdl-warn   { color: #b45309; }
.pdl-tradeoff {
  font-size: 12px; padding: 7px 10px; background: #fffbeb;
  border: 1px solid #fde68a; border-radius: 8px; color: #78350f;
}
.pdl-pval {
  font-size: 12px; padding: 6px 10px; background: #f0fdf4;
  border: 1px solid #bbf7d0; border-radius: 8px; color: #166534;
}
.pdl-pval-label { font-weight: 700; margin-right: 4px; }
@media (max-width: 560px) {
  .pdl-stats { grid-template-columns: repeat(2, 1fr); }
  .pdl-ctrl-row { flex-direction: column; }
}

/* ══════════════════════════════════════════════════════════════
   Phase 3B 批次2 — riemann / unit-circle / distribution / clt
══════════════════════════════════════════════════════════════ */

/* ── riemann-sum ── */
.rs-ctrl-row { display: flex; gap: 12px; flex-wrap: wrap; align-items: flex-start; }
.rs-mode-bar { display: flex; gap: 6px; }
.rs-mode {
  padding: 5px 12px; border-radius: 999px; font-size: 12px; font-weight: 700;
  background: white; color: var(--muted); border: 1px solid var(--line);
  cursor: pointer; min-height: unset; transition: all .12s;
}
.rs-mode.active { background: var(--accent); color: white; border-color: var(--accent); }
.rs-stats {
  display: grid; grid-template-columns: repeat(5, 1fr); gap: 6px;
}
.rs-stat {
  display: flex; flex-direction: column; gap: 2px; align-items: center;
  padding: 5px 4px; border-radius: 8px; background: #f8fafc;
  border: 1px solid #e2e8f0; font-size: 11px; color: var(--muted); text-align: center;
}
.rs-stat strong { font-size: 13px; color: var(--text); font-family: Consolas, monospace; }
.rs-good strong { color: #15803d; }
.rs-bad  strong { color: #b45309; }
.rs-type { grid-column: span 2; }
@media (max-width: 560px) {
  .rs-stats { grid-template-columns: repeat(2, 1fr); }
  .rs-type  { grid-column: span 2; }
}

/* ── unit-circle ── */
.uc-body { display: grid; grid-template-columns: 300px 1fr; gap: 12px; align-items: start; }
.uc-svg  { width: 100%; height: 300px; border-radius: 12px; background: white; border: 1px solid #dbeafe; }
.uc-info { display: flex; flex-direction: column; gap: 8px; }
.uc-vals { display: grid; gap: 4px; }
.uc-val-row {
  display: flex; justify-content: space-between; align-items: center;
  font-size: 12px; padding: 4px 8px; border-radius: 6px;
  background: #f8fafc; border: 1px solid #e2e8f0;
}
.uc-val-row code { font-size: 11px; font-family: Consolas, monospace; color: var(--accent); }
.uc-val-na { background: #fef2f2; border-color: #fecaca; }
.uc-val-na code { color: #b91c1c; }
.uc-vl { font-weight: 700; font-size: 12px; }
.uc-special-badge {
  padding: 5px 10px; border-radius: 8px;
  background: #fffbeb; border: 1px solid #fde68a;
  color: #854d0e; font-size: 12px; font-weight: 700;
}
.uc-ind-title { font-weight: 700; font-size: 12px; color: var(--accent); margin-bottom: 4px; }
.uc-ind-row {
  font-size: 11px; color: var(--muted); padding: 2px 0;
  border-bottom: 1px dashed var(--line);
}
@media (max-width: 620px) {
  .uc-body { grid-template-columns: 1fr; }
  .uc-svg  { height: 260px; }
}

/* ── distribution-plot ── */
.dst-tab-bar { display: flex; gap: 6px; flex-wrap: wrap; }
.dst-tab {
  padding: 5px 12px; border-radius: 999px; font-size: 12px; font-weight: 700;
  background: white; color: var(--muted); border: 1px solid var(--line);
  cursor: pointer; min-height: unset; transition: all .12s;
}
.dst-tab.active { background: #2563eb; color: white; border-color: #2563eb; }
.dst-stats { display: grid; grid-template-columns: 1fr 1fr; gap: 8px; }
.dst-stat {
  display: flex; flex-direction: column; gap: 2px; align-items: center;
  padding: 6px; border-radius: 8px; background: #eff6ff;
  border: 1px solid #bfdbfe; font-size: 11px; color: #1e40af; text-align: center;
}
.dst-stat strong { font-size: 14px; font-weight: 800; }

/* ── clt-demo ── */
.clt-stats { display: grid; grid-template-columns: repeat(4, 1fr); gap: 6px; }
.clt-stat {
  display: flex; flex-direction: column; gap: 2px; align-items: center;
  padding: 5px 4px; border-radius: 8px; background: #fff8e8;
  border: 1px solid #f1dfbd; font-size: 11px; color: var(--muted); text-align: center;
}
.clt-stat strong { font-size: 13px; color: var(--accent); font-family: Consolas, monospace; }
.clt-ratio { background: #f0fdf4; border-color: #bbf7d0; }
.clt-ratio strong { color: #15803d; }
@media (max-width: 560px) {
  .clt-stats { grid-template-columns: repeat(2, 1fr); }
  .dst-stats  { grid-template-columns: 1fr; }
}

/* ══════════════════════════════════════════════════════════════
   Phase 4A — 公式卡信息密度 + 关联卡片
══════════════════════════════════════════════════════════════ */

/* ── 两层折叠 details ── */
.card-details-core,
.card-details-secondary { margin-top: 10px; border-top: 1px dashed var(--line); padding-top: 8px; }

.card-details-core > summary {
  cursor: pointer; font-weight: 800; font-size: 13px; color: var(--accent);
  list-style: none; display: flex; align-items: center; gap: 6px;
}
.card-details-core > summary::before { content: "▶"; font-size: 10px; transition: transform .15s; }
.card-details-core[open] > summary::before { transform: rotate(90deg); }

.card-details-secondary > summary {
  cursor: pointer; font-weight: 600; font-size: 12px; color: var(--muted);
  list-style: none; display: flex; align-items: center; gap: 6px;
}
.card-details-secondary > summary::before { content: "▶"; font-size: 9px; transition: transform .15s; }
.card-details-secondary[open] > summary::before { transform: rotate(90deg); }

/* core grid: 用法(全宽) + 例子+易错(2列) + 演示(全宽) */
.dg-core {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 8px; margin-top: 10px;
}
.db-how,
.db-study { grid-column: 1 / -1; }         /* 怎么用/学习拆解：全宽 */
.db-demo { grid-column: 1 / -1; }          /* 演示：全宽 */
.db-mis  { background: #fef9f0; border-color: #fde68a; } /* 易错点：暖色提示 */
.db-mis h4 { color: #92400e; }

.db-study {
  background: linear-gradient(135deg, #fff7ed, #f8fafc);
  border-color: #fed7aa;
}
.study-head {
  display: flex; justify-content: space-between; align-items: center; gap: 8px;
  margin-bottom: 8px;
}
.study-head h4 { margin: 0; color: #9a3412; }
.study-head span {
  flex-shrink: 0; padding: 2px 8px; border-radius: 999px;
  background: #ffedd5; color: #9a3412; font-size: 10px; font-weight: 800;
}
.study-grid {
  display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 8px;
}
.study-grid section {
  padding: 9px 10px; border-radius: 12px;
  background: rgba(255,255,255,.72); border: 1px solid #fde68a;
}
.study-grid h5 {
  margin: 0 0 5px; font-size: 12px; color: #7c2d12;
}
.study-grid p,
.study-grid li {
  font-size: 12px; line-height: 1.7; color: #4b3b2b;
}
.study-grid p { margin: 0 0 6px; }
.study-grid ol,
.study-grid ul {
  margin: 0 0 0 18px; padding: 0;
}
.study-flow {
  display: flex; flex-wrap: wrap; gap: 5px; margin-top: 8px !important;
}
.study-flow span {
  display: inline-flex; align-items: center; padding: 2px 7px;
  border-radius: 999px; background: #fff7ed; border: 1px solid #fed7aa;
  color: #9a3412; font-size: 11px; font-weight: 700;
}

/* secondary grid: 2列 */
.dg-secondary { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 8px; margin-top: 10px; }

.db-guide {
  grid-column: 1 / -1;
  background: linear-gradient(135deg, #f5f3ff, #eff6ff);
  border-color: #c7d2fe;
}
.db-guide h4 { color: #4338ca; }
.db-guide ol {
  margin: 8px 0 0 18px;
  padding: 0;
  color: #374151;
  font-size: 12px;
  line-height: 1.7;
}
.db-guide li + li { margin-top: 3px; }

@media (max-width: 640px) {
  .dg-core      { grid-template-columns: 1fr; }
  .study-grid   { grid-template-columns: 1fr; }
  .dg-secondary { grid-template-columns: 1fr; }
}

/* ── 关联卡片 ── */
.rel-row {
  display: flex; flex-wrap: wrap; align-items: center; gap: 6px;
  margin: 6px 0 2px;
}
.rel-label { font-size: 11px; color: var(--muted); font-weight: 700; flex-shrink: 0; }
.rel-chip {
  padding: 3px 10px; border-radius: 999px; font-size: 11px; font-weight: 600;
  background: #eff6ff; color: #1d4ed8; border: 1px solid #bfdbfe;
  cursor: pointer; min-height: unset; transition: all .12s;
  max-width: 180px; overflow: hidden; text-overflow: ellipsis; white-space: nowrap;
}
.rel-chip:hover { background: #dbeafe; border-color: #93c5fd; }

/* ── 跳转高亮 ── */
@keyframes cardJump {
  0%   { outline: 3px solid #2563eb; outline-offset: 3px; background: #eff6ff; }
  70%  { outline: 3px solid #2563eb; outline-offset: 3px; }
  100% { outline: 3px solid transparent; background: transparent; }
}
.card-jump-highlight { animation: cardJump 1.4s ease forwards; }

/* ── 跳转 Toast ── */
.jump-toast {
  position: fixed; bottom: 72px; left: 50%; transform: translateX(-50%) translateY(12px);
  background: #1e293b; color: white; font-size: 13px; font-weight: 600;
  padding: 8px 18px; border-radius: 999px; z-index: var(--z-toast);
  opacity: 0; pointer-events: none; transition: opacity .2s, transform .2s;
  white-space: nowrap; max-width: 90vw; overflow: hidden; text-overflow: ellipsis;
}
.jump-toast.jump-toast-show { opacity: 1; transform: translateX(-50%) translateY(0); }

/* ══════════════════════════════════════════════════════════════
   Phase 4B — labsGrid thumbnail + Hero 今日推荐
══════════════════════════════════════════════════════════════ */

/* ── lab card thumbnail ── */
.lab-card-top {
  display: flex; gap: 8px; align-items: flex-start; margin-bottom: 6px;
}
.lab-thumb {
  width: 56px; height: 44px; flex-shrink: 0;
  border-radius: 8px; background: #f8fafc; border: 1px solid #e2e8f0;
}
.lab-card-meta {
  display: flex; flex-direction: column; align-items: flex-end; gap: 4px; flex: 1;
}
.lab-card-icon { font-size: 22px; line-height: 1; }
.lab-level {
  display: inline-block; padding: 2px 8px; border-radius: 999px;
  font-size: 10px; font-weight: 800; letter-spacing: .04em;
}
.lv-hot  { background: #fee2e2; color: #b91c1c; }
.lv-mid  { background: #dbeafe; color: #1d4ed8; }
.lv-ext  { background: #f3f4f6; color: #374151; }

/* ── Hero 今日推荐 ── */
.hero-recommend {
  margin-top: 14px; padding-top: 12px;
  border-top: 1px dashed var(--line);
}
.today-rec-title {
  font-size: 13px; font-weight: 800; color: var(--accent); margin-bottom: 8px;
}
.today-rec-list { display: flex; flex-direction: column; gap: 6px; }
.today-rec-item {
  display: flex; align-items: center; gap: 8px;
  padding: 6px 10px; border-radius: 10px;
  background: #fffdf8; border: 1px solid var(--line);
}
.today-rec-badge {
  flex-shrink: 0; padding: 2px 7px; border-radius: 999px;
  font-size: 10px; font-weight: 800;
}
.today-rec-badge.必背 { background: #fee2e2; color: #b91c1c; }
.today-rec-badge.常用 { background: #dbeafe; color: #1d4ed8; }
.today-rec-name { flex: 1; font-size: 13px; font-weight: 600; color: var(--text); }
.today-rec-btn {
  flex-shrink: 0; padding: 3px 10px; border-radius: 8px; font-size: 11px;
  font-weight: 700; background: var(--panel-strong); color: var(--accent);
  border: 1px solid var(--accent); min-height: unset; cursor: pointer;
}
.today-rec-btn:hover { background: var(--accent); color: white; }
.today-rec-empty { font-size: 13px; color: var(--green); font-weight: 700; }
@media (max-width: 640px) {
  .today-rec-name { font-size: 12px; }
}

/* ── Phase 4C: rel-chip keyboard focus ── */
.rel-chip:focus-visible {
  outline: 2px solid #2563eb;
  outline-offset: 2px;
  background: #dbeafe;
}