/* =====================================================================
 * 费马点互动课堂 · 样式表
 * 结构：变量 / 背景 / 外壳 / 顶栏 / 舞台 / 面板控件 / 字幕条 / 开场 / 弹窗 / 响应式
 * ===================================================================== */

/* ------------------------------------------------------------------
 * 1. 设计变量
 * ---------------------------------------------------------------- */
:root {
  --font-sans: -apple-system, BlinkMacSystemFont, "PingFang SC", "Hiragino Sans GB",
               "Microsoft YaHei", "Noto Sans SC", "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  --font-mono: ui-monospace, SFMono-Regular, "SF Mono", Menlo, Consolas, "Liberation Mono", monospace;
  --font-serif: "Songti SC", "Noto Serif SC", Georgia, "Times New Roman", serif;

  --r-sm: 8px; --r-md: 12px; --r-lg: 18px; --r-xl: 26px;
  --dur: .22s;
  --ease: cubic-bezier(.4, .12, .2, 1);
}

html[data-theme="dark"] {
  --bg: #060910;
  --bg-2: #0a1120;
  --surface: rgba(19, 27, 46, .58);
  --surface-2: rgba(28, 38, 62, .55);
  --line: rgba(255, 255, 255, .085);
  --line-2: rgba(255, 255, 255, .16);
  --ink: #e9eefb;
  --ink-2: #9db0d4;
  --ink-3: #6d80a6;
  --accent: #5eead4;
  --accent-2: #a78bfa;
  --c-a: #5eead4;
  --c-b: #fbbf24;
  --c-c: #fb7185;
  --c-p: #a78bfa;
  --ok: #4ade80;
  --warn: #fbbf24;
  --bad: #fb7185;
  --canvas-bg: linear-gradient(180deg, rgba(12, 20, 38, .55), rgba(8, 13, 26, .75));
  --shadow: 0 24px 60px -28px rgba(0, 0, 0, .95), inset 0 1px 0 rgba(255, 255, 255, .055);
  --shadow-sm: 0 8px 24px -14px rgba(0, 0, 0, .8);
  --grid: rgba(255, 255, 255, .055);
  --grid-2: rgba(255, 255, 255, .11);
  --glass: blur(18px) saturate(1.35);
  --hero-veil: radial-gradient(120% 90% at 50% 10%, rgba(6, 9, 16, .25) 0%, rgba(6, 9, 16, .86) 62%, rgba(4, 6, 12, .97) 100%);
}

html[data-theme="light"] {
  --bg: #eef1f8;
  --bg-2: #f7f9fd;
  --surface: rgba(255, 255, 255, .74);
  --surface-2: rgba(255, 255, 255, .6);
  --line: rgba(15, 30, 60, .1);
  --line-2: rgba(15, 30, 60, .2);
  --ink: #0f1b33;
  --ink-2: #46587a;
  --ink-3: #7386a6;
  --accent: #0d9488;
  --accent-2: #7c3aed;
  --c-a: #0d9488;
  --c-b: #d97706;
  --c-c: #e11d48;
  --c-p: #7c3aed;
  --ok: #16a34a;
  --warn: #d97706;
  --bad: #e11d48;
  --canvas-bg: linear-gradient(180deg, rgba(255, 255, 255, .8), rgba(238, 243, 252, .9));
  --shadow: 0 20px 50px -30px rgba(18, 38, 74, .45), inset 0 1px 0 rgba(255, 255, 255, .9);
  --shadow-sm: 0 8px 20px -14px rgba(18, 38, 74, .4);
  --grid: rgba(20, 40, 80, .07);
  --grid-2: rgba(20, 40, 80, .14);
  --glass: blur(18px) saturate(1.2);
  --hero-veil: radial-gradient(120% 90% at 50% 8%, rgba(238, 241, 248, .3) 0%, rgba(238, 241, 248, .88) 60%, rgba(233, 238, 247, .98) 100%);
}

* { box-sizing: border-box; }

html, body {
  height: 100%;
  margin: 0;
  padding: 0;
}

body {
  font-family: var(--font-sans);
  background: var(--bg);
  color: var(--ink);
  overflow: hidden;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  text-rendering: optimizeLegibility;
  transition: background .5s var(--ease), color .3s var(--ease);
}

a { color: inherit; text-decoration: none; }
button { font: inherit; color: inherit; }
h1, h2, h3, h4, p, ul, li { margin: 0; padding: 0; }
ul { list-style: none; }

::selection { background: color-mix(in srgb, var(--accent) 40%, transparent); }

::-webkit-scrollbar { width: 9px; height: 9px; }
::-webkit-scrollbar-track { background: transparent; }
::-webkit-scrollbar-thumb { background: var(--line-2); border-radius: 9px; border: 2px solid transparent; background-clip: padding-box; }
::-webkit-scrollbar-thumb:hover { background: var(--ink-3); background-clip: padding-box; }

:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; border-radius: 6px; }

/* ------------------------------------------------------------------
 * 2. 背景
 * ---------------------------------------------------------------- */
.backdrop { position: fixed; inset: 0; z-index: 0; pointer-events: none; overflow: hidden; }
html[data-theme="dark"] .backdrop {
  background:
    radial-gradient(90% 70% at 12% -5%, #16294d 0%, transparent 60%),
    radial-gradient(70% 60% at 95% 8%, #241a4d 0%, transparent 58%),
    linear-gradient(180deg, var(--bg-2), var(--bg) 70%);
}
html[data-theme="light"] .backdrop {
  background:
    radial-gradient(90% 70% at 10% -8%, #d6e6ff 0%, transparent 60%),
    radial-gradient(70% 60% at 96% 4%, #e8dcff 0%, transparent 55%),
    linear-gradient(180deg, var(--bg-2), var(--bg));
}
.orb {
  position: absolute; border-radius: 50%; filter: blur(70px); opacity: .5;
  animation: drift 34s var(--ease) infinite alternate;
}
html[data-theme="light"] .orb { opacity: .38; }
.orb-1 { width: 46vw; height: 46vw; left: -12vw; top: -14vw; background: radial-gradient(circle, #1e6f8f, transparent 70%); }
.orb-2 { width: 38vw; height: 38vw; right: -10vw; top: 18vh; background: radial-gradient(circle, #6d3fbf, transparent 70%); animation-duration: 44s; }
.orb-3 { width: 34vw; height: 34vw; left: 32vw; bottom: -16vw; background: radial-gradient(circle, #0f766e, transparent 70%); animation-duration: 52s; }
@keyframes drift {
  0%   { transform: translate3d(0, 0, 0) scale(1); }
  50%  { transform: translate3d(4vw, 3vh, 0) scale(1.12); }
  100% { transform: translate3d(-3vw, 5vh, 0) scale(.95); }
}
.grid-lines {
  position: absolute; inset: 0;
  background-image:
    linear-gradient(var(--grid) 1px, transparent 1px),
    linear-gradient(90deg, var(--grid) 1px, transparent 1px);
  background-size: 46px 46px;
  mask-image: radial-gradient(120% 100% at 50% 0%, #000 0%, transparent 78%);
  -webkit-mask-image: radial-gradient(120% 100% at 50% 0%, #000 0%, transparent 78%);
}
.noise {
  position: absolute; inset: 0; opacity: .5; mix-blend-mode: overlay;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='140' height='140'%3E%3Cfilter id='n'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='.85' numOctaves='3'/%3E%3C/filter%3E%3Crect width='140' height='140' filter='url(%23n)' opacity='.35'/%3E%3C/svg%3E");
}

/* ------------------------------------------------------------------
 * 3. 外壳布局
 * ---------------------------------------------------------------- */
.shell {
  position: relative; z-index: 1;
  height: 100vh; height: 100dvh;
  display: grid;
  grid-template-rows: auto minmax(0, 1fr) auto;
  padding: 10px 12px 10px;
  gap: 10px;
}
.shell.focus .rail, .shell.focus .panel, .shell.focus .stage-head, .shell.focus .stage-foot { display: none; }
.shell.focus .main { grid-template-columns: minmax(0, 1fr); }

/* ------------------------------------------------------------------
 * 4. 顶栏
 * ---------------------------------------------------------------- */
.topbar {
  display: flex; align-items: center; gap: 14px;
  padding: 8px 10px 8px 12px;
  border-radius: var(--r-lg);
  background: var(--surface);
  border: 1px solid var(--line);
  backdrop-filter: var(--glass); -webkit-backdrop-filter: var(--glass);
  box-shadow: var(--shadow-sm);
  min-height: 54px;
}
.brand { display: flex; align-items: center; gap: 10px; flex: none; }
.brand-mark {
  display: grid; place-items: center; width: 34px; height: 34px; border-radius: 11px;
  color: var(--accent);
  background: color-mix(in srgb, var(--accent) 14%, transparent);
  border: 1px solid color-mix(in srgb, var(--accent) 30%, transparent);
}
.brand-text { display: flex; flex-direction: column; line-height: 1.15; }
.brand-text b { font-size: 15px; letter-spacing: .06em; }
.brand-text i {
  font-style: normal; font-size: 9.5px; letter-spacing: .16em; text-transform: uppercase;
  color: var(--ink-3);
}

.chapnav {
  display: flex; gap: 4px; overflow-x: auto; overflow-y: hidden;
  flex: 1 1 auto; min-width: 0; padding: 2px;
  scrollbar-width: none; -ms-overflow-style: none;
  mask-image: linear-gradient(90deg, transparent 0, #000 14px, #000 calc(100% - 14px), transparent 100%);
  -webkit-mask-image: linear-gradient(90deg, transparent 0, #000 14px, #000 calc(100% - 14px), transparent 100%);
}
.chapnav::-webkit-scrollbar { display: none; }
.chip-nav {
  flex: none; display: flex; align-items: center; gap: 7px;
  padding: 6px 11px; border-radius: 999px;
  font-size: 12px; color: var(--ink-2);
  border: 1px solid transparent; background: transparent;
  cursor: pointer; white-space: nowrap;
  transition: background var(--dur) var(--ease), color var(--dur) var(--ease), border-color var(--dur) var(--ease);
}
.chip-nav .n {
  font-family: var(--font-mono); font-size: 10px; opacity: .65;
  padding: 1px 5px; border-radius: 5px; background: color-mix(in srgb, var(--ink-3) 18%, transparent);
}
.chip-nav:hover { background: color-mix(in srgb, var(--ink) 7%, transparent); color: var(--ink); }
.chip-nav.on {
  color: var(--ink); background: color-mix(in srgb, var(--accent) 15%, transparent);
  border-color: color-mix(in srgb, var(--accent) 38%, transparent);
  box-shadow: 0 0 0 1px color-mix(in srgb, var(--accent) 12%, transparent), 0 6px 18px -10px var(--accent);
}
.chip-nav.on .n { background: color-mix(in srgb, var(--accent) 26%, transparent); opacity: 1; color: var(--ink); }

.tools { display: flex; align-items: center; gap: 6px; flex: none; }
.tool {
  display: inline-flex; align-items: center; gap: 7px;
  height: 34px; padding: 0 12px; border-radius: 999px;
  font-size: 12.5px; font-weight: 600; color: var(--ink-2);
  background: color-mix(in srgb, var(--ink) 6%, transparent);
  border: 1px solid var(--line); cursor: pointer;
  transition: all var(--dur) var(--ease);
  white-space: nowrap;
}
.tool:hover { color: var(--ink); background: color-mix(in srgb, var(--ink) 11%, transparent); border-color: var(--line-2); }
.tool-icon { width: 34px; padding: 0; justify-content: center; font-size: 14px; }
.tool.on { color: var(--ink); background: color-mix(in srgb, var(--accent) 17%, transparent); border-color: color-mix(in srgb, var(--accent) 36%, transparent); }
.tool-play { background: linear-gradient(120deg, color-mix(in srgb, var(--accent) 88%, #000), color-mix(in srgb, var(--accent-2) 80%, #000)); color: #04121a; border-color: transparent; }
html[data-theme="light"] .tool-play { color: #fff; }
.tool-play:hover { filter: brightness(1.08); background: linear-gradient(120deg, color-mix(in srgb, var(--accent) 88%, #000), color-mix(in srgb, var(--accent-2) 80%, #000)); color: #04121a; }
.speed { display: flex; gap: 1px; padding: 2px; border-radius: 999px; background: color-mix(in srgb, var(--ink) 6%, transparent); border: 1px solid var(--line); }
.sp {
  border: 0; background: transparent; color: var(--ink-3); cursor: pointer;
  font-size: 10.5px; font-family: var(--font-mono); padding: 5px 7px; border-radius: 999px;
  transition: all var(--dur) var(--ease);
}
.sp:hover { color: var(--ink); }
.sp.on { color: var(--ink); background: color-mix(in srgb, var(--ink) 12%, transparent); }

/* ------------------------------------------------------------------
 * 5. 主区 / 舞台
 * ---------------------------------------------------------------- */
.main {
  display: grid;
  grid-template-columns: minmax(0, 1fr) 372px;
  gap: 10px; min-height: 0;
}
.stage {
  position: relative; min-width: 0; min-height: 0;
  display: grid; grid-template-rows: auto minmax(0, 1fr) auto; gap: 8px;
  padding: 12px 14px 10px;
  border-radius: var(--r-xl);
  background: var(--surface);
  border: 1px solid var(--line);
  backdrop-filter: var(--glass); -webkit-backdrop-filter: var(--glass);
  box-shadow: var(--shadow);
  overflow: hidden;
}
.stage::after {
  content: ""; position: absolute; inset: 0; pointer-events: none; border-radius: inherit;
  background: radial-gradient(120% 60% at 50% -10%, color-mix(in srgb, var(--accent) 8%, transparent), transparent 70%);
}
.stage-head { display: flex; align-items: flex-start; justify-content: space-between; gap: 12px; }
.stage-head-l { display: flex; align-items: baseline; gap: 12px; min-width: 0; }
.chapnum {
  font-family: var(--font-mono); font-size: 30px; font-weight: 700; line-height: 1;
  color: transparent; -webkit-text-stroke: 1.4px color-mix(in srgb, var(--accent) 62%, transparent);
  letter-spacing: -.02em; flex: none;
}
.stage-title { font-size: 19px; font-weight: 700; letter-spacing: .01em; }
.stage-kicker { font-size: 12.5px; color: var(--ink-2); margin-top: 3px; line-height: 1.5; }
.stage-head-r { display: flex; gap: 6px; flex-wrap: wrap; justify-content: flex-end; }
.badge {
  font-size: 11px; padding: 4px 9px; border-radius: 999px;
  border: 1px solid var(--line-2); color: var(--ink-2);
  background: color-mix(in srgb, var(--ink) 5%, transparent); white-space: nowrap;
}
.badge.ok { color: var(--ok); border-color: color-mix(in srgb, var(--ok) 40%, transparent); background: color-mix(in srgb, var(--ok) 12%, transparent); }
.badge.warn { color: var(--warn); border-color: color-mix(in srgb, var(--warn) 40%, transparent); background: color-mix(in srgb, var(--warn) 12%, transparent); }
.badge.bad { color: var(--bad); border-color: color-mix(in srgb, var(--bad) 40%, transparent); background: color-mix(in srgb, var(--bad) 12%, transparent); }

.stage-body { position: relative; min-height: 0; display: grid; grid-template-rows: minmax(0, 1fr); }
.stage-body > * { min-height: 0; min-width: 0; }
.stage-foot {
  display: flex; align-items: center; gap: 8px;
  font-size: 11.5px; color: var(--ink-3);
}
.hintdot { width: 5px; height: 5px; border-radius: 50%; background: var(--accent); box-shadow: 0 0 8px var(--accent); flex: none; }

/* 画布容器通用件 */
.canvas-box {
  position: relative; min-width: 0; min-height: 0;
  border-radius: var(--r-lg); overflow: hidden;
  background: var(--canvas-bg);
  border: 1px solid var(--line);
  box-shadow: var(--shadow-sm);
}
.canvas-box canvas { position: absolute; inset: 0; width: 100%; height: 100%; display: block; touch-action: none; }
.canvas-box.grabbing canvas { cursor: grabbing !important; }
.hud { position: absolute; display: flex; gap: 6px; flex-wrap: wrap; pointer-events: none; }
.hud.tl { top: 10px; left: 10px; }
.hud.tr { top: 10px; right: 10px; justify-content: flex-end; }
.hud.bl { bottom: 10px; left: 10px; }
.hud.br { bottom: 10px; right: 10px; justify-content: flex-end; }
.hud .chip {
  pointer-events: auto;
  font-size: 11px; font-family: var(--font-mono);
  padding: 4px 9px; border-radius: 8px;
  background: color-mix(in srgb, var(--bg) 62%, transparent);
  border: 1px solid var(--line);
  backdrop-filter: blur(8px); -webkit-backdrop-filter: blur(8px);
  color: var(--ink-2); cursor: pointer;
  transition: all var(--dur) var(--ease);
}
.hud .chip:hover { color: var(--ink); border-color: var(--line-2); }
.hud .chip.on { color: var(--ink); background: color-mix(in srgb, var(--accent) 22%, transparent); border-color: color-mix(in srgb, var(--accent) 45%, transparent); }
.hud .chip.plain { cursor: default; }

.viz-grid {
  display: grid; gap: 10px; min-height: 0; min-width: 0; height: 100%;
  grid-auto-rows: minmax(0, 1fr);   /* 没有显式指定行时也必须撑满，否则 canvas 高度为 0 */
}
.viz-grid.g-side { grid-template-columns: minmax(0, 1fr) minmax(240px, 330px); }
.viz-grid.g-two { grid-template-columns: minmax(0, 1fr) minmax(0, 1fr); }
.viz-grid.g-stack { grid-template-rows: minmax(0, 1fr) auto; }
.viz-grid.g-rows { grid-template-rows: minmax(0, 1fr) 190px; }
.viz-grid.g-rows-sm { grid-template-rows: minmax(0, 1fr) 150px; }
.chart-box { position: relative; min-height: 0; }
.chart-box canvas { position: absolute; inset: 0; width: 100%; height: 100%; display: block; touch-action: none; cursor: ew-resize; }

/* ------------------------------------------------------------------
 * 6. 右侧讲解面板
 * ---------------------------------------------------------------- */
.panel {
  min-height: 0; overflow-y: auto; overflow-x: hidden;
  padding: 16px 16px 22px;
  border-radius: var(--r-xl);
  background: var(--surface);
  border: 1px solid var(--line);
  backdrop-filter: var(--glass); -webkit-backdrop-filter: var(--glass);
  box-shadow: var(--shadow);
  display: flex; flex-direction: column; gap: 12px;
  scroll-behavior: smooth;
}
.panel > * { flex-shrink: 0; } /* 缩放/矮窗口时让面板滚动，而不是把公式等块压扁 */
.pnl-h { display: flex; align-items: baseline; gap: 8px; }
.pnl-h h2 { font-size: 12px; font-weight: 700; letter-spacing: .16em; text-transform: uppercase; color: var(--ink-3); }
.pnl-h-sub { font-size: 11px; color: var(--ink-3); }
.pnl-p {
  font-size: 13.5px; line-height: 1.78; color: var(--ink-2);
  padding: 8px 10px; margin: -4px -10px; border-radius: 10px;
  transition: background .35s var(--ease), color .35s var(--ease), box-shadow .35s var(--ease);
}
.pnl-p b { color: var(--ink); font-weight: 650; }
.pnl-p .hl { color: var(--accent); font-weight: 650; }
.pnl-p.focus {
  background: color-mix(in srgb, var(--accent) 10%, transparent);
  box-shadow: inset 2px 0 0 var(--accent);
  color: var(--ink);
}
.pnl-p code, .pnl-note code, .help-p code {
  font-family: var(--font-mono); font-size: .92em;
  background: color-mix(in srgb, var(--ink) 8%, transparent);
  padding: 1px 5px; border-radius: 5px;
}
.pnl-note { font-size: 12px; line-height: 1.7; color: var(--ink-3); }
.pnl-ul { display: flex; flex-direction: column; gap: 6px; }
.pnl-ul li {
  font-size: 12.5px; line-height: 1.65; color: var(--ink-2);
  padding-left: 16px; position: relative;
}
.pnl-ul li::before {
  content: ""; position: absolute; left: 3px; top: 8px;
  width: 5px; height: 5px; border-radius: 50%; background: var(--accent); opacity: .7;
}
.pnl-hr { height: 1px; background: var(--line); margin: 2px 0; }

.card {
  padding: 12px; border-radius: var(--r-md);
  background: color-mix(in srgb, var(--ink) 4%, transparent);
  border: 1px solid var(--line);
  display: flex; flex-direction: column; gap: 9px;
}
.card.tight { gap: 7px; padding: 10px; }
.card-title { font-size: 11.5px; font-weight: 700; letter-spacing: .1em; text-transform: uppercase; color: var(--ink-3); }

.formula {
  padding: 13px 12px; border-radius: var(--r-md);
  background: color-mix(in srgb, var(--ink) 4%, transparent);
  border: 1px solid var(--line);
  overflow-x: auto; overflow-y: hidden;
}
.formula-body { font-family: var(--font-serif); font-size: 16px; line-height: 1.6; color: var(--ink); }
.formula-body math { font-size: 1.02em; }
.formula-cap { font-size: 11px; color: var(--ink-3); margin-top: 8px; line-height: 1.6; }
.mvar { font-style: italic; }
.mop { color: var(--accent); }

/* 读数 */
.ro-row { display: grid; grid-template-columns: repeat(auto-fit, minmax(96px, 1fr)); gap: 8px; }
.ro {
  padding: 9px 11px; border-radius: var(--r-md);
  background: color-mix(in srgb, var(--ink) 4%, transparent);
  border: 1px solid var(--line);
  min-width: 0;
}
.ro-label { font-size: 10.5px; color: var(--ink-3); letter-spacing: .06em; }
.ro-val {
  font-family: var(--font-mono); font-size: 21px; font-weight: 650; line-height: 1.25;
  color: var(--ink); margin-top: 2px;
  font-variant-numeric: tabular-nums;
  overflow: hidden; text-overflow: ellipsis; white-space: nowrap;
}
.ro-val .u { font-size: 11px; color: var(--ink-3); font-weight: 500; margin-left: 3px; }
.ro-sub { font-size: 10.5px; color: var(--ink-3); margin-top: 1px; min-height: 14px; }
.ro.accent .ro-val { color: var(--accent); }
.ro.ok .ro-val { color: var(--ok); }
.ro.warn .ro-val { color: var(--warn); }
.ro.bad .ro-val { color: var(--bad); }

/* 控件 */
.ctl { display: block; }
.sl-wrap { display: flex; flex-direction: column; gap: 6px; }
.sl-head { display: flex; align-items: baseline; justify-content: space-between; gap: 8px; }
.sl-label { font-size: 11.5px; color: var(--ink-2); }
.sl-val { font-family: var(--font-mono); font-size: 11.5px; color: var(--ink); }
input.sl {
  -webkit-appearance: none; appearance: none; width: 100%; height: 18px;
  background: transparent; cursor: pointer; margin: 0;
}
input.sl::-webkit-slider-runnable-track {
  height: 4px; border-radius: 4px;
  background: linear-gradient(90deg, color-mix(in srgb, var(--accent) 55%, transparent), color-mix(in srgb, var(--ink) 12%, transparent));
}
input.sl::-webkit-slider-thumb {
  -webkit-appearance: none; appearance: none;
  width: 14px; height: 14px; border-radius: 50%; margin-top: -5px;
  background: var(--accent); border: 2px solid var(--bg);
  box-shadow: 0 2px 8px -2px var(--accent);
  transition: transform .15s var(--ease);
}
input.sl:hover::-webkit-slider-thumb { transform: scale(1.18); }
input.sl::-moz-range-track { height: 4px; border-radius: 4px; background: color-mix(in srgb, var(--ink) 14%, transparent); }
input.sl::-moz-range-progress { height: 4px; border-radius: 4px; background: color-mix(in srgb, var(--accent) 55%, transparent); }
input.sl::-moz-range-thumb { width: 12px; height: 12px; border-radius: 50%; background: var(--accent); border: 2px solid var(--bg); }

.tg {
  display: flex; align-items: center; gap: 9px; width: 100%;
  padding: 7px 10px; border-radius: var(--r-md);
  background: color-mix(in srgb, var(--ink) 4%, transparent);
  border: 1px solid var(--line); cursor: pointer; text-align: left;
  transition: all var(--dur) var(--ease);
}
.tg:hover { border-color: var(--line-2); }
.tg-sw {
  position: relative; width: 32px; height: 18px; border-radius: 999px; flex: none;
  background: color-mix(in srgb, var(--ink) 16%, transparent);
  transition: background var(--dur) var(--ease);
}
.tg-knob {
  position: absolute; top: 2px; left: 2px; width: 14px; height: 14px; border-radius: 50%;
  background: var(--ink-2); transition: all var(--dur) var(--ease);
}
.tg.on .tg-sw { background: color-mix(in srgb, var(--accent) 60%, transparent); }
.tg.on .tg-knob { left: 16px; background: #fff; }
.tg-label { font-size: 12px; color: var(--ink-2); }
.tg.on .tg-label { color: var(--ink); }

.btn {
  display: inline-flex; align-items: center; justify-content: center; gap: 7px;
  padding: 8px 14px; border-radius: 999px;
  font-size: 12.5px; font-weight: 600; color: var(--ink);
  background: color-mix(in srgb, var(--ink) 7%, transparent);
  border: 1px solid var(--line); cursor: pointer;
  transition: all var(--dur) var(--ease);
}
.btn:hover { background: color-mix(in srgb, var(--ink) 12%, transparent); border-color: var(--line-2); transform: translateY(-1px); }
.btn:active { transform: translateY(0); }
.btn:disabled { opacity: .4; cursor: not-allowed; transform: none; }
.btn.primary {
  background: linear-gradient(120deg, color-mix(in srgb, var(--accent) 85%, #000), color-mix(in srgb, var(--accent-2) 75%, #000));
  color: #05131a; border-color: transparent;
}
html[data-theme="light"] .btn.primary { color: #fff; }
.btn.ghost { background: transparent; }
.btn.sm { padding: 6px 11px; font-size: 11.5px; }

.seg { display: flex; gap: 2px; padding: 3px; border-radius: 999px; background: color-mix(in srgb, var(--ink) 6%, transparent); border: 1px solid var(--line); }
.sg-btn {
  flex: 1; border: 0; background: transparent; color: var(--ink-3); cursor: pointer;
  font-size: 11.5px; padding: 6px 8px; border-radius: 999px; white-space: nowrap;
  transition: all var(--dur) var(--ease);
}
.sg-btn:hover { color: var(--ink); }
.sg-btn.on { color: var(--ink); background: color-mix(in srgb, var(--ink) 13%, transparent); box-shadow: var(--shadow-sm); }

.chips { display: flex; gap: 6px; flex-wrap: wrap; }
.chip {
  padding: 5px 11px; border-radius: 999px; font-size: 11.5px;
  color: var(--ink-3); background: color-mix(in srgb, var(--ink) 5%, transparent);
  border: 1px solid var(--line); cursor: pointer;
  transition: all var(--dur) var(--ease);
}
.chip:hover { color: var(--ink); border-color: var(--line-2); }
.chip.on { color: var(--ink); background: color-mix(in srgb, var(--accent) 16%, transparent); border-color: color-mix(in srgb, var(--accent) 38%, transparent); }

.hint { font-size: 11.5px; line-height: 1.6; color: var(--ink-3); }

/* ------------------------------------------------------------------
 * 7. 字幕条 / 播放控制
 * ---------------------------------------------------------------- */
.caption {
  display: flex; align-items: center; gap: 12px;
  padding: 9px 16px; border-radius: var(--r-lg);
  background: var(--surface);
  border: 1px solid var(--line);
  backdrop-filter: var(--glass); -webkit-backdrop-filter: var(--glass);
  box-shadow: var(--shadow-sm);
  min-height: 62px;
}
.cap-left { flex: none; }
.cap-toggle {
  width: 40px; height: 40px; border-radius: 50%; display: grid; place-items: center;
  font-size: 14px; cursor: pointer; color: #05131a; border: 0;
  background: linear-gradient(130deg, color-mix(in srgb, var(--accent) 88%, #000), color-mix(in srgb, var(--accent-2) 82%, #000));
  box-shadow: 0 8px 22px -10px var(--accent);
  transition: transform var(--dur) var(--ease);
}
.cap-toggle:hover { transform: scale(1.06); }
.cap-mid { flex: 1 1 auto; min-width: 0; }
.cap-text {
  font-size: 13.5px; line-height: 1.6; color: var(--ink);
  min-height: 22px;
  transition: opacity .25s var(--ease);
}
.cap-text.swap { opacity: 0; }
.cap-text .who { color: var(--accent); font-weight: 650; }
.cap-track { display: flex; gap: 3px; margin-top: 7px; height: 4px; }
.cap-tick {
  flex: 1; border-radius: 3px; background: color-mix(in srgb, var(--ink) 12%, transparent);
  overflow: hidden; cursor: pointer; position: relative;
  transition: background var(--dur) var(--ease);
}
.cap-tick:hover { background: color-mix(in srgb, var(--ink) 22%, transparent); }
.cap-tick i { position: absolute; inset: 0; width: 0%; background: var(--accent); border-radius: 3px; display: block; }
.cap-tick.done i { width: 100%; background: color-mix(in srgb, var(--accent) 55%, transparent); }
.cap-right { flex: none; display: flex; align-items: center; gap: 10px; }
.cap-resume {
  font-size: 11.5px; padding: 5px 11px; border-radius: 999px; cursor: pointer;
  color: var(--warn); background: color-mix(in srgb, var(--warn) 14%, transparent);
  border: 1px solid color-mix(in srgb, var(--warn) 38%, transparent);
  animation: pulse 1.8s var(--ease) infinite;
}
@keyframes pulse { 0%, 100% { opacity: 1; } 50% { opacity: .55; } }
.cap-time { font-family: var(--font-mono); font-size: 11px; color: var(--ink-3); min-width: 42px; text-align: right; }

/* ------------------------------------------------------------------
 * 8. 开场页
 * ---------------------------------------------------------------- */
.hero {
  position: fixed; inset: 0; z-index: 50;
  display: grid; place-items: center;
  padding: 24px;
  transition: opacity .7s var(--ease), visibility .7s;
}
.hero.gone { opacity: 0; visibility: hidden; pointer-events: none; }
.hero-canvas { position: absolute; inset: 0; width: 100%; height: 100%; }
.hero-veil { position: absolute; inset: 0; background: var(--hero-veil); }
.hero-content {
  position: relative; z-index: 2; max-width: 720px; text-align: center;
  animation: rise .9s var(--ease) both;
}
@keyframes rise { from { opacity: 0; transform: translateY(18px); } to { opacity: 1; transform: none; } }
.hero-eyebrow {
  font-size: 11.5px; letter-spacing: .26em; text-transform: uppercase;
  color: var(--accent); margin-bottom: 18px;
}
.hero-title {
  font-size: clamp(38px, 8vw, 74px); font-weight: 800; letter-spacing: .02em; line-height: 1.05;
  background: linear-gradient(120deg, var(--ink) 10%, var(--accent) 50%, var(--accent-2) 92%);
  -webkit-background-clip: text; background-clip: text; color: transparent;
  display: flex; flex-direction: column; align-items: center; gap: 8px;
}
.hero-title-en {
  font-size: clamp(11px, 1.6vw, 14px); font-weight: 600; letter-spacing: .34em;
  -webkit-text-fill-color: var(--ink-3); color: var(--ink-3);
}
.hero-lead { font-size: clamp(13.5px, 1.5vw, 16px); line-height: 1.9; color: var(--ink-2); margin: 22px auto 30px; max-width: 560px; }
.hero-lead b { color: var(--ink); }
.hero-cta { display: flex; gap: 12px; justify-content: center; flex-wrap: wrap; }
.btn-hero {
  padding: 14px 30px; font-size: 14.5px; font-weight: 700; color: #05131a; border: 0;
  background: linear-gradient(120deg, color-mix(in srgb, var(--accent) 90%, #000), color-mix(in srgb, var(--accent-2) 82%, #000));
  box-shadow: 0 18px 44px -18px var(--accent);
}
html[data-theme="light"] .btn-hero { color: #fff; }
.btn-hero:hover { transform: translateY(-2px); filter: brightness(1.06); }
.btn-ghost { padding: 14px 24px; font-size: 14px; }
.hero-feats {
  display: flex; gap: 10px; justify-content: center; flex-wrap: wrap;
  margin-top: 34px; font-size: 11.5px; color: var(--ink-3);
}
.hero-feats li {
  padding: 6px 13px; border-radius: 999px;
  border: 1px solid var(--line); background: color-mix(in srgb, var(--bg) 40%, transparent);
  backdrop-filter: blur(8px); -webkit-backdrop-filter: blur(8px);
}
.hero-chapters { display: flex; gap: 6px; justify-content: center; flex-wrap: wrap; margin-top: 22px; }
.hero-chapters button {
  font-size: 11px; padding: 5px 11px; border-radius: 999px; cursor: pointer;
  color: var(--ink-3); background: transparent; border: 1px solid var(--line);
  font-family: var(--font-mono);
  transition: all var(--dur) var(--ease);
}
.hero-chapters button:hover { color: var(--ink); border-color: var(--accent); background: color-mix(in srgb, var(--accent) 12%, transparent); }

/* ------------------------------------------------------------------
 * 9. 弹窗 / 提示
 * ---------------------------------------------------------------- */
.modal { position: fixed; inset: 0; z-index: 60; display: grid; place-items: center; padding: 24px; background: color-mix(in srgb, var(--bg) 72%, transparent); backdrop-filter: blur(8px); }
.modal[hidden] { display: none; }
.modal-box {
  position: relative; max-width: 560px; width: 100%; max-height: 82vh; overflow-y: auto;
  padding: 26px 28px; border-radius: var(--r-xl);
  background: var(--bg-2); border: 1px solid var(--line-2); box-shadow: var(--shadow);
}
.modal-box h3 { font-size: 12px; letter-spacing: .16em; text-transform: uppercase; color: var(--ink-3); margin: 18px 0 10px; }
.modal-box h3:first-child { margin-top: 0; }
.modal-x { position: absolute; top: 14px; right: 16px; width: 30px; height: 30px; border-radius: 50%; border: 1px solid var(--line); background: transparent; cursor: pointer; color: var(--ink-2); }
.modal-x:hover { color: var(--ink); border-color: var(--line-2); }
.help-list { display: flex; flex-direction: column; gap: 9px; }
.help-list li { font-size: 13px; line-height: 1.75; color: var(--ink-2); padding-left: 15px; position: relative; }
.help-list li::before { content: "▸"; position: absolute; left: 0; color: var(--accent); }
.help-list b { color: var(--ink); }
.keys { display: flex; flex-wrap: wrap; gap: 8px 16px; font-size: 12px; color: var(--ink-2); }
kbd {
  font-family: var(--font-mono); font-size: 11px; padding: 2px 7px; border-radius: 6px;
  background: color-mix(in srgb, var(--ink) 9%, transparent); border: 1px solid var(--line-2);
  margin-right: 3px; color: var(--ink);
}
.help-p { font-size: 12.5px; line-height: 1.8; color: var(--ink-2); }
.noscript {
  position: fixed; inset: 0; display: grid; place-items: center; z-index: 99;
  background: var(--bg); color: var(--ink); font-size: 15px; padding: 30px; text-align: center;
}

/* ------------------------------------------------------------------
 * 10. 小工具类
 * ---------------------------------------------------------------- */
.mono { font-family: var(--font-mono); }
.tiny { font-size: 11px; }
.muted { color: var(--ink-3); }
.center { text-align: center; }
.row { display: flex; gap: 8px; align-items: center; flex-wrap: wrap; }
.grow { flex: 1 1 auto; }
.ta-c { color: var(--c-a); } .ta-b { color: var(--c-b); } .ta-c2 { color: var(--c-c); } .ta-p { color: var(--c-p); }

.toast {
  position: fixed; left: 50%; bottom: 96px; transform: translate(-50%, 12px);
  z-index: 40; padding: 9px 16px; border-radius: 999px; font-size: 12.5px;
  background: var(--bg-2); border: 1px solid var(--line-2); color: var(--ink);
  box-shadow: var(--shadow); opacity: 0; pointer-events: none;
  transition: all .3s var(--ease);
}
.toast.show { opacity: 1; transform: translate(-50%, 0); }

/* 章节要点网格（总结章） */
.map-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(210px, 1fr)); gap: 10px; height: 100%; align-content: center; overflow-y: auto; }
.map-card {
  padding: 14px; border-radius: var(--r-md); cursor: pointer; text-align: left;
  background: color-mix(in srgb, var(--ink) 4%, transparent);
  border: 1px solid var(--line);
  transition: all var(--dur) var(--ease);
  display: flex; flex-direction: column; gap: 6px;
}
.map-card:hover { transform: translateY(-2px); border-color: color-mix(in srgb, var(--accent) 40%, transparent); background: color-mix(in srgb, var(--accent) 8%, transparent); }
.map-card .mc-k { font-family: var(--font-mono); font-size: 10.5px; color: var(--accent); letter-spacing: .1em; }
.map-card .mc-t { font-size: 14px; font-weight: 650; color: var(--ink); }
.map-card .mc-d { font-size: 11.5px; line-height: 1.6; color: var(--ink-3); }

.quiz { display: flex; flex-direction: column; gap: 10px; height: 100%; overflow-y: auto; }
.quiz-q { padding: 13px; border-radius: var(--r-md); border: 1px solid var(--line); background: color-mix(in srgb, var(--ink) 3%, transparent); }
.quiz-q .q-t { font-size: 13.5px; line-height: 1.7; color: var(--ink); margin-bottom: 9px; }
.quiz-opt {
  display: block; width: 100%; text-align: left; margin-top: 6px;
  padding: 8px 12px; border-radius: 10px; font-size: 12.5px; cursor: pointer;
  background: color-mix(in srgb, var(--ink) 4%, transparent); border: 1px solid var(--line); color: var(--ink-2);
  transition: all var(--dur) var(--ease);
}
.quiz-opt:hover { border-color: var(--line-2); color: var(--ink); }
.quiz-opt.right { border-color: color-mix(in srgb, var(--ok) 55%, transparent); background: color-mix(in srgb, var(--ok) 13%, transparent); color: var(--ink); }
.quiz-opt.wrong { border-color: color-mix(in srgb, var(--bad) 50%, transparent); background: color-mix(in srgb, var(--bad) 11%, transparent); }
.quiz-exp { margin-top: 9px; font-size: 11.5px; line-height: 1.7; color: var(--ink-3); }

/* ------------------------------------------------------------------
 * 11. 响应式
 * ---------------------------------------------------------------- */
@media (max-width: 1180px) {
  .main { grid-template-columns: minmax(0, 1fr) 320px; }
  .viz-grid.g-side { grid-template-columns: minmax(0, 1fr); grid-template-rows: minmax(0, 1fr) 190px; }
  .viz-grid.g-two { grid-template-columns: minmax(0, 1fr); grid-template-rows: minmax(0, 1fr) minmax(0, 1fr); }
}
@media (max-width: 900px) {
  body { overflow: auto; }
  .shell { height: auto; min-height: 100dvh; grid-template-rows: auto auto auto; }
  .main { grid-template-columns: minmax(0, 1fr); }
  .stage { min-height: 62vh; }
  .panel { max-height: none; }
  .tool-txt, #btnNext { display: none; }
  .chapnum { font-size: 22px; }
  .viz-grid.g-side, .viz-grid.g-two { grid-template-columns: minmax(0, 1fr); }
  .caption { position: sticky; bottom: 0; z-index: 20; }
}

@media (prefers-reduced-motion: reduce) {
  .orb { animation: none; }
  *, *::before, *::after { animation-duration: .01ms !important; transition-duration: .01ms !important; }
}