/* 星辰学会 · 教师端原型（2026-10-30）
   两部分：① 备课页（目录、选题、课件编辑）沿用全站 tokens.css / site.css 的纸墨外观；
          ② 投屏外壳 .pres：按 1920×1080 排版、整体缩放，字号和对比度按教室后排能看清来定。
   原型阶段只在预览站用；定稿时并入 site.css。 */

/* ========== ① 备课页 ========== */
.t-app { min-height: 100vh; display: flex; flex-direction: column; }
.t-app main { flex: 1; }
.t-app > .container { width: 100%; }   /* 竖排 flex 里左右 auto 外边距会让它缩成内容宽，这里撑满再由 max-width 限宽 */
.t-head__role { margin-left: var(--sp-2); padding: 2px 10px; border-radius: var(--r-pill); background: var(--night); color: #fff; font-size: var(--fs-14); font-weight: 600; letter-spacing: .04em; }
.t-page { padding-top: var(--sp-5); padding-bottom: var(--sp-8); }
.t-wide { max-width: 1480px; }
.t-title { margin-top: var(--sp-2); font-size: var(--fs-26); line-height: var(--lh-tight); font-weight: 700; color: var(--night); }
.t-lede { margin-top: var(--sp-2); max-width: 46em; color: var(--ink-2); }
.t-proto { display: inline-flex; align-items: center; margin-left: var(--sp-2); padding: 1px 8px; border: 1px dashed var(--line-strong); border-radius: var(--r-pill); font-size: var(--fs-14); font-weight: 500; color: var(--ink-3); vertical-align: middle; }
@media (min-width: 1024px) { .t-title { font-size: var(--fs-34); } }

.t-tabs { display: flex; flex-wrap: wrap; gap: var(--sp-2); margin: var(--sp-5) 0 var(--sp-4); }
.t-tab { display: inline-flex; align-items: center; gap: 8px; min-height: 44px; padding: 0 18px; border: 1px solid var(--line); border-radius: var(--r-pill); background: var(--surface); color: var(--ink-2); font-size: var(--fs-16); }
.t-tab::before { content: ""; width: 9px; height: 9px; border-radius: 50%; background: var(--subject, var(--ink-3)); }
.t-tab[aria-pressed="true"] { background: var(--night); border-color: var(--night); color: #fff; font-weight: 600; }
.t-tab small { font-size: var(--fs-14); opacity: .8; }

.t-note { font-size: var(--fs-14); color: var(--ink-3); }
.t-note b { color: var(--ink-2); font-weight: 600; }

/* 入口三张卡 */
.t-hub { display: grid; gap: var(--sp-4); margin-top: var(--sp-6); }
@media (min-width: 900px) { .t-hub { grid-template-columns: repeat(3, minmax(0, 1fr)); gap: var(--sp-5); } }
.t-hub__card { display: flex; flex-direction: column; gap: var(--sp-3); padding: var(--sp-5); background: var(--surface); border: 1px solid var(--line); border-radius: var(--r-l); box-shadow: var(--shadow-1); transition: box-shadow var(--t-fast), transform var(--t-fast); }
a.t-hub__card:hover { box-shadow: var(--shadow-2); transform: translateY(-1px); }
.t-hub__icon { width: 44px; height: 44px; border-radius: var(--r-m); background: var(--night-tint); display: grid; place-items: center; }
.t-hub__icon svg { width: 26px; height: 26px; fill: none; stroke: var(--night); stroke-width: 1.7; stroke-linecap: round; stroke-linejoin: round; }
.t-hub__name { font-size: var(--fs-22); font-weight: 700; color: var(--night); }
.t-hub__text { color: var(--ink-2); }
.t-hub__list { display: grid; gap: 4px; font-size: var(--fs-15); color: var(--ink-2); }
.t-hub__list li { display: flex; gap: 8px; }
.t-hub__list li::before { content: "·"; color: var(--star); font-weight: 700; }
.t-hub__go { margin-top: auto; font-weight: 600; color: var(--night); }
.t-facts { display: grid; gap: var(--sp-3); margin-top: var(--sp-6); padding: var(--sp-4) var(--sp-5); border: 1px dashed var(--line-strong); border-radius: var(--r-l); font-size: var(--fs-15); color: var(--ink-2); }
@media (min-width: 900px) { .t-facts { grid-template-columns: repeat(3, minmax(0, 1fr)); } }
.t-facts h2 { font-size: var(--fs-16); color: var(--ink); margin-bottom: 4px; }

/* 演示目录：章 → 知识点 → 演示卡 */
.t-chapter { margin-top: var(--sp-6); }
.t-chapter__title { display: flex; flex-wrap: wrap; align-items: baseline; gap: 4px var(--sp-3); font-size: var(--fs-20); font-weight: 700; padding-bottom: var(--sp-2); border-bottom: 2px solid var(--subject, var(--line)); }
.t-chapter__title small { font-size: var(--fs-14); font-weight: 400; color: var(--ink-3); }
.t-star { display: grid; gap: var(--sp-3); padding: var(--sp-4) 0; border-bottom: 1px solid var(--line); }
@media (min-width: 1024px) { .t-star { grid-template-columns: 15em minmax(0, 1fr); gap: var(--sp-5); } }
.t-star__name { font-size: var(--fs-18); font-weight: 600; }
.t-star__id { display: block; font-size: var(--fs-14); color: var(--ink-3); font-variant-numeric: tabular-nums; }
.t-star__sum { margin-top: 4px; font-size: var(--fs-15); color: var(--ink-2); }
.t-demos { display: grid; gap: var(--sp-3); grid-template-columns: repeat(auto-fill, minmax(240px, 1fr)); }
.t-demo { display: flex; flex-direction: column; gap: var(--sp-2); padding: var(--sp-2) var(--sp-2) var(--sp-3); background: var(--surface); border: 1px solid var(--line); border-radius: var(--r-m); transition: box-shadow var(--t-fast), border-color var(--t-fast); }
.t-demo > div:last-child { padding: 0 var(--sp-2); }
.t-demo:hover { box-shadow: var(--shadow-2); border-color: var(--line-strong); }
.t-demo__img { position: relative; aspect-ratio: 16 / 9; border-radius: var(--r-s); overflow: hidden; background: #151a21; }
.t-demo__img img { width: 100%; height: 100%; object-fit: cover; }
.t-demo__img--lab { display: grid; place-items: center; background: var(--s-math-tint); }
.t-demo__img--lab svg { width: 64%; height: auto; }
.t-demo__kind { position: absolute; left: 6px; top: 6px; padding: 0 7px; border-radius: var(--r-pill); background: rgba(17, 22, 34, .82); color: #fff; font-size: 12px; line-height: 20px; }
.t-demo__title { font-size: var(--fs-16); font-weight: 600; line-height: var(--lh-title); }
.t-demo__meta { font-size: var(--fs-14); color: var(--ink-3); }
.t-demo__go { display: inline-flex; align-items: center; gap: 6px; margin-top: 4px; font-size: var(--fs-15); font-weight: 600; color: var(--night); }
.t-demo__go svg { width: 14px; height: 14px; fill: currentColor; }

/* 试卷评讲：选题与错因 */
.t-grid2 { display: grid; gap: var(--sp-5); margin-top: var(--sp-4); }
@media (min-width: 1100px) { .t-grid2 { grid-template-columns: minmax(0, 1fr) 360px; align-items: start; } }
.t-qlist { display: grid; gap: var(--sp-2); }
/* 题号按原卷题型分组（董事长 11-01）：每组上方一行小标题（试卷评讲的题目列表、讲评课件的选题列表都用） */
.t-qgroup { margin: var(--sp-3) 0 0; font-size: var(--fs-14); font-weight: 700; letter-spacing: .04em; color: var(--ink-2); }
.t-qgroup:first-child { margin-top: 0; }
.t-q { background: var(--surface); border: 1px solid var(--line); border-radius: var(--r-m); }
.t-q.is-on { border-color: var(--night); box-shadow: 0 0 0 1px var(--night) inset; }
.t-q__row { display: grid; grid-template-columns: auto minmax(0, 1fr) auto; gap: var(--sp-3); align-items: center; padding: var(--sp-3) var(--sp-4); }
.t-check { position: relative; display: inline-flex; align-items: center; gap: 10px; cursor: pointer; }
.t-check input { width: 22px; height: 22px; margin: 0; accent-color: var(--night); cursor: pointer; }
.t-q__no { font-size: var(--fs-18); font-weight: 700; color: var(--night); font-variant-numeric: tabular-nums; min-width: 3.2em; }
.t-q__main { min-width: 0; }
.t-q__stem { font-size: var(--fs-15); color: var(--ink); overflow: hidden; display: -webkit-box; -webkit-line-clamp: 2; -webkit-box-orient: vertical; line-height: 1.6; }
.t-q__meta { margin-top: 2px; font-size: var(--fs-14); color: var(--ink-3); }
.t-q__side { text-align: right; font-size: var(--fs-14); color: var(--ink-3); white-space: nowrap; font-variant-numeric: tabular-nums; }
.t-q__side b { display: block; font-size: var(--fs-16); color: var(--ink); }
.t-badge { display: inline-flex; align-items: center; padding: 0 8px; border-radius: var(--r-pill); font-size: 13px; line-height: 22px; background: var(--surface-2); color: var(--ink-2); }
.t-badge--seg { background: var(--ok-tint); color: var(--ok); }
.t-badge--card { background: var(--key-tint); color: var(--key); }
.t-misc { display: grid; gap: 6px; padding: 0 var(--sp-4) var(--sp-3) calc(var(--sp-4) + 32px); }
.t-misc[hidden] { display: none; }
.t-misc__head { font-size: var(--fs-14); color: var(--ink-3); }
.t-misc label { display: grid; grid-template-columns: auto minmax(0, 1fr) auto; gap: 10px; align-items: start; padding: 6px 10px; border-radius: var(--r-s); background: var(--surface-2); cursor: pointer; font-size: var(--fs-15); }
.t-misc label:hover { background: var(--night-tint); }
.t-misc input { width: 18px; height: 18px; margin: 3px 0 0; accent-color: var(--night); }
.t-misc__text b { font-weight: 600; }
.t-misc__text small { display: block; color: var(--ink-3); font-size: var(--fs-14); }
.t-misc__dur { font-size: var(--fs-14); color: var(--ink-3); font-variant-numeric: tabular-nums; }
.t-sum { position: sticky; top: calc(var(--header-h) + var(--sp-3)); display: grid; gap: var(--sp-3); padding: var(--sp-5); background: var(--surface); border: 1px solid var(--line); border-radius: var(--r-l); box-shadow: var(--shadow-1); }
.t-sum__big { font-size: var(--fs-28); font-weight: 700; color: var(--night); font-variant-numeric: tabular-nums; line-height: 1.2; }
.t-sum__rows { display: grid; gap: 4px; font-size: var(--fs-15); color: var(--ink-2); }
.t-sum__rows b { color: var(--ink); }
.t-sum__list { max-height: 260px; overflow: auto; display: grid; gap: 2px; font-size: var(--fs-14); color: var(--ink-2); border-top: 1px solid var(--line); padding-top: var(--sp-2); }
.t-sum__btns { display: grid; gap: var(--sp-2); }
.t-tools { display: flex; flex-wrap: wrap; gap: var(--sp-2); margin-bottom: var(--sp-3); }

/* 讲评课件：页列表 */
.t-deck { display: grid; gap: var(--sp-5); margin-top: var(--sp-4); }
@media (min-width: 1100px) { .t-deck { grid-template-columns: 320px minmax(0, 1fr); align-items: start; } }
.t-qpick { display: grid; gap: 6px; max-height: 70vh; overflow: auto; }
.t-qpick button { display: grid; grid-template-columns: 3.4em minmax(0, 1fr); gap: 8px; align-items: baseline; text-align: left; padding: 8px 12px; border: 1px solid var(--line); border-radius: var(--r-s); background: var(--surface); }
.t-qpick button[aria-pressed="true"] { border-color: var(--night); background: var(--night-tint); }
.t-qpick button b { color: var(--night); font-variant-numeric: tabular-nums; }
.t-qpick button span { font-size: var(--fs-14); color: var(--ink-2); overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.t-qpick button small { grid-column: 2; font-size: 13px; color: var(--ink-3); }
.t-slides { display: grid; gap: var(--sp-3); grid-template-columns: repeat(auto-fill, minmax(250px, 1fr)); }
.t-slide { display: flex; flex-direction: column; background: var(--surface); border: 1px solid var(--line); border-radius: var(--r-m); overflow: hidden; }
.t-slide.is-off { opacity: .45; }
.t-slide__thumb { position: relative; aspect-ratio: 16 / 9; overflow: hidden; background: #12161c; cursor: zoom-in; }
.t-slide__thumb .pres__mini { position: absolute; left: 0; top: 0; width: 1920px; height: 1080px; transform-origin: 0 0; pointer-events: none; }
.t-slide__bar { display: flex; align-items: center; gap: 6px; padding: 6px 8px; border-top: 1px solid var(--line); font-size: var(--fs-14); }
.t-slide__n { font-weight: 700; color: var(--night); font-variant-numeric: tabular-nums; }
.t-slide__name { flex: 1; min-width: 0; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; color: var(--ink-2); }
.t-ibtn { display: inline-grid; place-items: center; width: 32px; height: 32px; border: 1px solid var(--line); border-radius: var(--r-s); background: var(--surface); color: var(--ink-2); font-size: 15px; }
.t-ibtn:hover { border-color: var(--line-strong); color: var(--night); }
.t-ibtn[aria-pressed="false"] { color: var(--ink-3); }
.t-slide__note { margin: 0 8px 8px; }
.t-slide__note textarea { width: 100%; min-height: 40px; resize: vertical; font: inherit; font-size: var(--fs-14); padding: 6px 8px; border: 1px solid var(--line); border-radius: var(--r-s); background: var(--bg); color: var(--ink); }
.t-files { display: grid; gap: var(--sp-2); margin-top: var(--sp-3); font-size: var(--fs-15); }
.t-files a { color: var(--night); font-weight: 600; }

.t-foot { margin-top: var(--sp-7); padding: var(--sp-4) 0 var(--sp-6); border-top: 1px solid var(--line); font-size: var(--fs-14); color: var(--ink-3); }
.t-foot p + p { margin-top: 4px; }
.t-foot a { color: var(--night); }

/* ========== ② 投屏外壳 ========== */
.pres, .pres-vars {
  /* 深色板：与讲解视频同一块「黑板」，颜色 = 含义（视频组件库 theme.py） */
  --p-bg: #0E1116; --p-board: #141920; --p-board-2: #10141A;
  --p-ink: #ECEAE3; --p-dim: #AEB5BF; --p-faint: #6F7782; --p-line: rgba(236, 234, 227, .16);
  --p-key: #EBC46A; --p-key-tint: rgba(235, 196, 106, .14);
  --p-bad: #F38C80; --p-bad-tint: rgba(243, 140, 128, .12);
  --p-ok: #63D8BE; --p-ok-tint: rgba(99, 216, 190, .12);
  --p-violet: #B79BFF; --p-rose: #FF8DB3; --p-sky: #7CC8FF; --p-amber: #F6AE5A; --p-teal: #63D8BE;
  --p-card: rgba(255, 255, 255, .045); --p-mask: #232A34; --p-mask-line: rgba(236, 234, 227, .10);
  --p-chrome: rgba(16, 20, 26, .92); --p-chrome-ink: #ECEAE3; --p-chrome-dim: #AEB5BF;
  color: var(--p-ink); font-family: var(--font); -webkit-font-smoothing: antialiased;
}
.pres { position: fixed; inset: 0; margin: 0; overflow: hidden; background: var(--p-bg); user-select: none; -webkit-user-select: none; }
.pres [hidden], .pres-vars [hidden] { display: none !important; }
.pres *, .pres *::before, .pres *::after, .pres-vars *, .pres-vars *::before, .pres-vars *::after { box-sizing: border-box; }
.pres p, .pres h3, .pres figure, .pres-vars p, .pres-vars figure, .pres-vars h3 { margin: 0; }
.pres.theme-light, .pres-vars.theme-light {
  /* 浅色板：教室光线亮时用。文字对比度 ≥ 7:1 */
  --p-bg: #E9E7E1; --p-board: #FBFAF6; --p-board-2: #F4F2EC;
  --p-ink: #14181F; --p-dim: #464D57; --p-faint: #8A8F96; --p-line: rgba(20, 24, 31, .14);
  --p-key: #7A4F00; --p-key-tint: rgba(217, 169, 75, .20);
  --p-bad: #A11F17; --p-bad-tint: rgba(227, 149, 141, .20);
  --p-ok: #075E51; --p-ok-tint: rgba(95, 174, 156, .18);
  --p-violet: #5E35B8; --p-rose: #A3204F; --p-sky: #1452AE; --p-amber: #A65108; --p-teal: #075E51;
  --p-card: rgba(20, 24, 31, .035); --p-mask: #E4E1D8; --p-mask-line: rgba(20, 24, 31, .08);
}
.pres button { font-family: var(--font); }
.pres__viewport { position: absolute; inset: 0; }
.pres__stage {
  position: absolute; left: 50%; top: 50%; width: 1920px; height: 1080px; transform-origin: 50% 50%;
  background: radial-gradient(120% 90% at 30% 20%, var(--p-board), var(--p-board-2)); overflow: hidden;
}
.pres__content { position: absolute; left: 0; top: 0; width: 1920px; height: 1080px; }
.pres__content.has-foot { height: 1032px; }
.pres__ink { position: absolute; left: 0; top: 0; width: 1920px; height: 1080px; pointer-events: none; touch-action: none; z-index: 5; }
.pres.is-pen .pres__ink { pointer-events: auto; cursor: crosshair; }
.pres.is-eraser .pres__ink { pointer-events: auto; cursor: cell; }
.pres__foot {
  position: absolute; left: 0; right: 0; bottom: 0; height: 48px; z-index: 4; display: flex; align-items: center; gap: 24px;
  padding: 0 56px; font-size: 22px; color: var(--p-dim); border-top: 1px solid var(--p-line); background: var(--p-board-2);
  white-space: nowrap; overflow: hidden;
}
.pres__foot.is-over { border-top: 0; background: linear-gradient(to top, rgba(14, 17, 22, .86), rgba(14, 17, 22, 0)); color: #C9CED6; height: 56px; }
.pres__foot span { overflow: hidden; text-overflow: ellipsis; }
.pres__foot .pres__foot-r { margin-left: auto; flex: none; }
.pres__blank { position: absolute; inset: 0; z-index: 30; background: #000; }
.pres__blank.is-white { background: #fff; }

/* 幕布：从上往下拉，遮住还不想让学生看的部分 */
.pres__curtain { position: absolute; left: 0; right: 0; top: 0; height: 540px; z-index: 6;
  background: repeating-linear-gradient(135deg, var(--p-mask) 0 22px, color-mix(in srgb, var(--p-mask) 86%, var(--p-ink)) 22px 24px); box-shadow: 0 6px 24px rgba(0, 0, 0, .35); }
.pres__curtain-handle { position: absolute; left: 50%; bottom: -30px; transform: translateX(-50%); display: flex; align-items: center; gap: 10px; height: 60px; padding: 0 28px;
  border-radius: 30px; background: var(--p-mask); border: 2px solid var(--p-line); color: var(--p-dim); font-size: 24px; cursor: ns-resize; touch-action: none; }

/* 计时器：在画面右上角，后排也看得见 */
.pres__timer { position: absolute; right: 40px; top: 32px; z-index: 7; display: flex; align-items: center; gap: 14px; padding: 6px 30px 10px; border-radius: 22px;
  background: var(--p-board-2); border: 2px solid var(--p-line); font-size: 88px; font-weight: 700; font-variant-numeric: tabular-nums; letter-spacing: .02em; line-height: 1.1; color: var(--p-ink); box-shadow: 0 6px 24px rgba(0, 0, 0, .25); }
.pres__timer small { font-size: 26px; font-weight: 600; color: var(--p-dim); letter-spacing: .1em; }
.pres__timer.is-warn { color: var(--p-amber); border-color: var(--p-amber); }
.pres__timer.is-up { color: var(--p-key); border-color: var(--p-key); animation: pres-pulse 1s ease-in-out 3; }
@keyframes pres-pulse { 50% { transform: scale(1.06); } }

/* 外壳的控件（不在 1920×1080 画面里，按屏幕像素排；鼠标不动 3 秒后隐去） */
.pres__top, .pres__bar { position: absolute; left: 0; right: 0; z-index: 20; transition: opacity .25s, transform .25s; }
.pres__top { top: 0; display: flex; align-items: center; gap: 14px; padding: 10px 16px; background: linear-gradient(to bottom, var(--p-chrome), rgba(16, 20, 26, 0)); color: var(--p-chrome-ink); font-size: 17px; }
.pres__crumb { min-width: 0; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.pres__crumb b { font-weight: 700; }
.pres__crumb span { color: var(--p-chrome-dim); }
.pres__count { margin-left: auto; flex: none; color: var(--p-chrome-dim); font-variant-numeric: tabular-nums; }
.pres__bar { bottom: 0; display: flex; justify-content: center; padding: 10px 12px 14px; pointer-events: none; }
.pres__tools { pointer-events: auto; display: flex; flex-wrap: wrap; justify-content: center; align-items: center; gap: 4px; max-width: 100%; padding: 6px; border-radius: 18px; background: var(--p-chrome); box-shadow: 0 8px 28px rgba(0, 0, 0, .35); border: 1px solid rgba(255, 255, 255, .08); }
.pres.is-idle .pres__top, .pres.is-idle .pres__bar { opacity: 0; pointer-events: none; }
.pres.is-idle .pres__top { transform: translateY(-8px); }
.pres.is-idle .pres__bar { transform: translateY(8px); }
.pres.is-idle .pres__tools { pointer-events: none; }
.pres.is-idle { cursor: none; }
.pres.is-idle.is-pen, .pres.is-idle.is-eraser { cursor: crosshair; }
.pbtn { display: inline-flex; flex-direction: column; align-items: center; justify-content: center; gap: 2px; min-width: 56px; min-height: 52px; padding: 4px 10px; border: 0; border-radius: 12px; background: transparent; color: var(--p-chrome-ink); font-size: 13px; line-height: 1.2; }
.pbtn svg { width: 22px; height: 22px; fill: none; stroke: currentColor; stroke-width: 1.8; stroke-linecap: round; stroke-linejoin: round; }
.pbtn:hover { background: rgba(255, 255, 255, .09); }
.pbtn[aria-pressed="true"] { background: #ECEAE3; color: #10141A; }
.pbtn:disabled { opacity: .35; cursor: default; background: transparent; }
.pbtn--wide { flex-direction: row; gap: 8px; font-size: 16px; min-width: 112px; }
.pbtn--go { background: #ECEAE3; color: #10141A; font-weight: 700; }
.pbtn--go:hover { background: #fff; }
.pres__sep { width: 1px; align-self: stretch; margin: 6px 4px; background: rgba(255, 255, 255, .14); }
.pres__swatches { display: none; gap: 4px; padding: 0 4px; }
.pres.is-pen .pres__swatches { display: inline-flex; }
.pres__sw { width: 30px; height: 30px; border-radius: 50%; border: 3px solid transparent; background: var(--c); }
.pres__sw[aria-pressed="true"] { border-color: #fff; box-shadow: 0 0 0 2px #10141A inset; }
.pres__chips { display: flex; flex-wrap: wrap; gap: 4px; padding: 0 4px; max-width: 760px; }
.pres__chip { min-height: 36px; padding: 0 12px; border-radius: 18px; border: 1px solid rgba(255, 255, 255, .18); background: transparent; color: var(--p-chrome-ink); font-size: 14px; }
.pres__chip.is-rec { border-color: #EBC46A; color: #F4DA9A; }
.pres__chip.is-now { background: #ECEAE3; color: #10141A; border-color: #ECEAE3; }
.pres__pop { position: absolute; bottom: 92px; left: 50%; transform: translateX(-50%); z-index: 25; padding: 14px; border-radius: 16px; background: var(--p-chrome); color: var(--p-chrome-ink);
  box-shadow: 0 8px 28px rgba(0, 0, 0, .4); border: 1px solid rgba(255, 255, 255, .1); font-size: 15px; }
.pres__pop h3 { margin: 0 0 10px; font-size: 15px; font-weight: 600; color: var(--p-chrome-dim); }
.pres__pop-row { display: flex; flex-wrap: wrap; gap: 6px; align-items: center; }
.pres__pop-row + .pres__pop-row { margin-top: 8px; }
.pres__pop button.pres__chip { min-width: 64px; }
.pres__toc { position: absolute; top: 0; right: 0; bottom: 0; z-index: 26; width: min(420px, 92vw); overflow: auto; padding: 20px 18px 40px; background: var(--p-chrome); color: var(--p-chrome-ink); box-shadow: -8px 0 28px rgba(0, 0, 0, .4); }
.pres__toc h3 { margin: 18px 0 6px; font-size: 15px; color: var(--p-chrome-dim); font-weight: 600; }
.pres__toc h3:first-child { margin-top: 0; }
.pres__toc button { display: grid; grid-template-columns: 2.2em minmax(0, 1fr) auto; gap: 8px; width: 100%; padding: 8px 10px; border: 0; border-radius: 10px; background: transparent; color: inherit; font-size: 16px; text-align: left; }
.pres__toc button:hover { background: rgba(255, 255, 255, .08); }
.pres__toc button.is-now { background: #ECEAE3; color: #10141A; }
.pres__toc button i { font-style: normal; color: var(--p-chrome-dim); font-variant-numeric: tabular-nums; }
.pres__toc button.is-now i { color: #4E5661; }
.pres__toc button small { font-size: 13px; color: var(--p-chrome-dim); font-variant-numeric: tabular-nums; }
.pres__notes { position: absolute; left: 16px; bottom: 96px; z-index: 24; width: min(560px, 60vw); max-height: 40vh; overflow: auto; padding: 14px 16px; border-radius: 14px; background: #FFF8E1; color: #2A2310; font-size: 16px; line-height: 1.6; box-shadow: 0 8px 28px rgba(0, 0, 0, .35); }
.pres__notes h3 { margin: 0 0 6px; font-size: 14px; color: #6B5A1E; }
.pres__hint { position: absolute; left: 50%; top: 64px; transform: translateX(-50%); z-index: 22; padding: 8px 18px; border-radius: 20px; background: var(--p-chrome); color: var(--p-chrome-ink); font-size: 16px; pointer-events: none; transition: opacity .3s; }
.pres__help { position: absolute; left: 50%; top: 50%; transform: translate(-50%, -50%); z-index: 27; width: min(640px, 92vw); padding: 22px 26px; border-radius: 18px; background: var(--p-chrome); color: var(--p-chrome-ink); box-shadow: 0 8px 28px rgba(0, 0, 0, .45); font-size: 16px; }
.pres__help dl { display: grid; grid-template-columns: 9em 1fr; gap: 6px 14px; margin: 10px 0 0; }
.pres__help dt { color: #F4DA9A; font-variant-numeric: tabular-nums; }
.pres__help dd { margin: 0; }
.pres__x, .pres__toc .pres__x { position: absolute; top: 10px; right: 12px; display: block; width: 40px; height: 40px; padding: 0; border: 0; border-radius: 10px; background: transparent; color: inherit; font-size: 22px; text-align: center; }
.pres__toc .pres__x + h3 { margin-top: 32px; }

/* ---------- 画面里的内容（1920×1080 设计稿像素） ---------- */
.pv { position: absolute; inset: 0; }
.pv video, .pv img.pv__full { position: absolute; inset: 0; width: 100%; height: 100%; object-fit: contain; background: transparent; }
.pv__big { position: absolute; left: 50%; top: 50%; width: 132px; height: 132px; margin: -66px 0 0 -66px; border-radius: 50%; border: 0; background: rgba(236, 234, 227, .92); display: grid; place-items: center; z-index: 2; }
.pv__big svg { width: 58px; height: 58px; fill: #10141A; margin-left: 8px; }
.pv__bar { position: absolute; left: 0; right: 0; bottom: 0; height: 6px; background: rgba(255, 255, 255, .08); z-index: 2; }
.pv__fill { height: 100%; width: 0; background: var(--p-key); }
.pv iframe { position: absolute; inset: 0; width: 100%; height: 100%; border: 0; background: #fff; }

/* 文字页：所有字号 ≥ 26px；正文 44px，题干 48px */
.ps { position: absolute; inset: 0; padding: 84px 120px 64px; display: flex; flex-direction: column; font-size: 44px; line-height: 1.6; color: var(--p-ink); }
.ps__kicker { display: flex; align-items: center; gap: 18px; font-size: 30px; font-weight: 700; letter-spacing: .08em; color: var(--p-dim); }
.ps__kicker i { width: 14px; height: 14px; border-radius: 50%; background: var(--k, var(--p-key)); flex: none; }
.ps__kicker small { font-size: 26px; font-weight: 400; letter-spacing: .02em; color: var(--p-faint); }
.ps__title { margin-top: 18px; font-size: 60px; line-height: 1.3; font-weight: 700; }
.ps__body { margin-top: 36px; flex: 1; min-height: 0; display: flex; flex-direction: column; gap: 22px; }
.ps__cols { display: grid; grid-template-columns: minmax(0, 1fr) auto; gap: 64px; align-items: start; }
.ps__fig { max-width: 620px; padding: 22px; border-radius: 20px; background: #fff; }
.ps__fig img { max-height: 620px; width: auto; max-width: 100%; }
.ps__fig figcaption { margin-top: 8px; font-size: 26px; color: #4E5661; text-align: center; }
.ps__stem { font-size: 48px; line-height: 1.75; }
.ps__stem p + p { margin-top: 10px; }
.ps__opts { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 14px 48px; margin-top: 18px; font-size: 48px; }
.ps__opts.is-long { grid-template-columns: minmax(0, 1fr); }
.ps__opt { display: flex; gap: 22px; align-items: baseline; padding: 10px 24px; border-radius: 16px; border: 2px solid transparent; }
.ps__opt > b { flex: none; color: var(--p-dim); font-weight: 700; }
.ps__opt.is-key { border-color: var(--p-key); background: var(--p-key-tint); }
.ps__opt.is-key > b { color: var(--p-key); }
.ps__opt.is-dim { opacity: .55; }
.ps__list { display: grid; gap: 18px; padding: 0; margin: 0; list-style: none; }
.ps__list li { display: grid; grid-template-columns: 36px minmax(0, 1fr); gap: 18px; }
.ps__list li::before { content: ""; width: 14px; height: 14px; margin-top: 27px; border-radius: 50%; background: var(--p-dim); }
.ps__line { display: grid; grid-template-columns: 64px minmax(0, 1fr); gap: 18px; align-items: baseline; padding: 20px 28px; border-radius: 20px; font-size: 46px; }
.ps__line > i { font-style: normal; font-weight: 800; font-size: 50px; }
.ps__line--bad { background: var(--p-bad-tint); }
.ps__line--bad > i { color: var(--p-bad); }
.ps__line--ok { background: var(--p-ok-tint); }
.ps__line--ok > i { color: var(--p-ok); }
.ps__quote { padding: 34px 44px; border-radius: 22px; background: var(--p-card); border: 2px solid var(--p-line); font-size: 46px; line-height: 1.7; }
.ps__src { margin-top: 18px; font-size: 30px; color: var(--p-dim); }
.ps__card { padding: 30px 40px; border-radius: 22px; border: 3px solid var(--p-key); background: var(--p-key-tint); }
.ps__card h3 { margin: 0 0 12px; font-size: 32px; letter-spacing: .08em; color: var(--p-key); }
.ps__note { position: absolute; right: 64px; bottom: 76px; max-width: 760px; padding: 18px 26px; border-radius: 16px; background: #FFF3C4; color: #2A2310; font-size: 34px; line-height: 1.5; box-shadow: 0 6px 20px rgba(0, 0, 0, .25); transform: rotate(-.6deg); }
.ps__note b { display: block; font-size: 26px; color: #6B5A1E; letter-spacing: .08em; }
.ps__tags { display: flex; flex-wrap: wrap; gap: 14px; }
.ps__tag { padding: 6px 22px; border-radius: 999px; border: 2px solid var(--p-line); font-size: 32px; color: var(--p-ink); }
.ps__step { color: var(--p-dim); }
.ps--mid .ps__body { justify-content: center; padding-bottom: 80px; }
.ps__quote--book { border-left: 10px solid var(--p-key); }
.ps__cols--fig { grid-template-columns: minmax(0, 1fr) 500px; gap: 56px; }
.ps__col { display: flex; flex-direction: column; gap: 22px; min-width: 0; }
.ps__fig--side { max-width: none; padding: 18px; }
.ps__fig--side img { display: block; width: 100%; height: auto; max-height: 600px; object-fit: contain; }
.ps__steps { display: flex; flex-direction: column; gap: 16px; }
.ps__res { color: var(--p-key); font-weight: 700; }
.frag { opacity: 0; transform: translateY(10px); transition: opacity .3s ease-out, transform .3s ease-out; }
.frag.is-in { opacity: 1; transform: none; }
.pres__mini .frag { opacity: 1; transform: none; transition: none; }
.ps--sum .ps__title--big { margin-top: 36px; font-size: 72px; line-height: 1.35; }
.ps__cards { display: grid; grid-auto-flow: column; grid-auto-columns: minmax(0, 1fr); gap: 32px; }
.ps__card--alt { border-color: var(--p-sky); background: rgba(124, 200, 255, .10); }
.ps__card--alt h3 { color: var(--p-sky); }
.ps__tagrow { margin-top: auto; display: flex; flex-wrap: wrap; align-items: center; gap: 16px 24px; }
.ps__tagrow .ps__sub { margin: 0; }
.ps__figs { display: flex; flex-direction: column; gap: 20px; align-items: flex-end; }
.ps.is-scroll { overflow-y: auto; }
.ps.is-scroll::after { content: "内容较长：滚动看下面"; position: sticky; bottom: -40px; align-self: flex-end; padding: 6px 16px; border-radius: 12px; background: var(--p-board-2); color: var(--p-dim); font-size: 24px; }
.ps__ansline { display: flex; align-items: baseline; gap: 28px; font-size: 52px; }
.ps__ansline > b { flex: none; }
.ps__ansline .ans { min-width: 6em; min-height: 1.4em; }
.ps__pts { display: grid; gap: 16px; padding: 0; margin: 0; list-style: none; font-size: 38px; line-height: 1.55; }
.ps__pts li { display: grid; grid-template-columns: 52px minmax(0, 1fr); gap: 16px; align-items: start; }
.ps__pts li > i { font-style: normal; display: grid; place-items: center; width: 46px; height: 46px; margin-top: 6px; border-radius: 50%; border: 2px solid var(--p-line); font-size: 26px; font-weight: 700; color: var(--p-dim); }
.ps__pts .ans { min-height: 1.55em; }
.ps__hl { color: var(--p-key); font-weight: 700; }
.ps b, .ps strong { font-weight: 700; }
.ps .katex { font-size: 1.04em; }
.ps table { border-collapse: collapse; font-size: 36px; }
.ps td, .ps th { border: 2px solid var(--p-line); padding: 8px 18px; }

/* 封面：只写题号、题型、考什么，不写答案 */
.ps--cover { justify-content: center; align-items: center; text-align: center; padding-bottom: 120px; }
.ps--cover .ps__eyebrow { font-size: 34px; letter-spacing: .14em; color: var(--p-key); font-weight: 600; }
.ps--cover .ps__no { margin-top: 24px; font-size: 168px; line-height: 1.05; font-weight: 800; letter-spacing: .04em; }
.ps--cover .ps__meta { margin-top: 20px; font-size: 40px; color: var(--p-dim); }
.ps--cover .ps__rule { width: 520px; height: 3px; margin: 44px auto 30px; background: var(--p-key); opacity: .8; }
.ps--cover .ps__what { font-size: 34px; color: var(--p-dim); }
.ps--cover .ps__whatbig { margin-top: 10px; font-size: 54px; font-weight: 700; }

/* 遮住的答案：点一下才显示 */
.ans { position: relative; display: inline-block; min-width: 3.2em; border-radius: 12px; cursor: pointer; vertical-align: baseline; }
.ans--block { display: block; }
.ans:not(.is-shown) { background: repeating-linear-gradient(135deg, var(--p-mask) 0 16px, transparent 16px 18px), var(--p-mask); outline: 2px dashed var(--p-mask-line); }
.ans:not(.is-shown) > * { visibility: hidden; }
.ans:not(.is-shown)::after { content: attr(data-label); position: absolute; inset: 0; display: grid; place-items: center; font-size: 28px; font-weight: 600; letter-spacing: .06em; color: var(--p-dim); white-space: nowrap; }
.ans.is-shown { animation: ans-in .35s ease-out; }
@keyframes ans-in { from { opacity: .2; } to { opacity: 1; } }

/* 课堂提问（链路里的小判断，在课上变成全班一起答） */
.ps__probe .ps__opt { cursor: default; }
.ps__explain { margin-top: 10px; padding: 22px 30px; border-radius: 18px; background: var(--p-ok-tint); font-size: 40px; }

/* 题卡（还没有讲解片段的题）、过题卡 */
.ps--gap { justify-content: center; }
.ps__big { font-size: 64px; font-weight: 700; }
.ps__sub { margin-top: 18px; font-size: 36px; color: var(--p-dim); }

/* 缩略图：同一份页面按 1920×1080 排好再缩小；不要动画 */
.pres__mini { background: radial-gradient(120% 90% at 30% 20%, var(--p-board), var(--p-board-2)); color: var(--p-ink); }
.pres__mini .ans.is-shown { animation: none; }
.t-slide__thumb video { position: absolute; inset: 0; width: 100%; height: 100%; object-fit: cover; }