@font-face{font-family:"TikTok Sans";src:url("assets/fonts/TikTokSans-Variable.woff2") format("woff2");font-weight:300 900;font-stretch:75% 150%;font-style:normal;font-display:swap}
/* Palette sampled from 三线.pdf: charcoal, cyan, lime, white. */
:root{
  color-scheme:dark;
  --font:"TikTok Sans","PingFang SC","Microsoft YaHei",sans-serif;
  --bg:oklch(.301184 0 0); /* #2E2E2E */
  --ink:oklch(1 0 0);
  --muted:oklch(.798372 0 0);
  --border:oklch(.492609 0 0);
  --accent:oklch(.902447 .155729 190.2106); /* #00FFF6 */
  --line:oklch(.856780 .193559 114.6351); /* #CEDD00 */
  --line-label:oklch(.954708 .2156 114.5886); /* #EEFF00 */
  --panel:oklch(.243535 0 0); /* #202020 */
  --soft-cyan:oklch(.812969 .072787 195.8139); /* #88D1D1 */
  --header:color-mix(in srgb,var(--accent) 30%,var(--bg));
  --selected:color-mix(in srgb,var(--accent) 14%,var(--panel));
  --hover:color-mix(in srgb,var(--ink) 8%,var(--panel));
  --control-border:color-mix(in srgb,var(--ink) 45%,var(--panel));
  --media-white:oklch(1 0 0);
  --media-gray:oklch(.952131 0 0);
  --scrim:oklch(0 0 0 / .7)
}
*{box-sizing:border-box}
body{margin:0;background:var(--bg);color:var(--ink);font:14px/1.5 var(--font);font-synthesis:none;font-optical-sizing:auto;-webkit-font-smoothing:antialiased;-moz-osx-font-smoothing:grayscale}
button,select,input{font:inherit}button,select{min-height:44px;border:1px solid var(--control-border);border-radius:8px;padding:10px 14px;background:var(--panel);color:var(--ink)}button{cursor:pointer}button:disabled{opacity:.4;cursor:default}
/* Match the text's left inset and the chevron's right inset across every select. */
select{
  --select-inset:14px;
  -webkit-appearance:none;appearance:none;
  padding-left:var(--select-inset);
  padding-right:calc(var(--select-inset) + 12px + 12px);
  background-image:url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='8' viewBox='0 0 12 8'%3E%3Cpath d='m1 1 5 5 5-5' fill='none' stroke='white' stroke-width='1.5' stroke-linecap='round' stroke-linejoin='round'/%3E%3C/svg%3E");
  background-repeat:no-repeat;
  background-position:right var(--select-inset) center;
  background-size:12px 8px;
}
button:focus-visible,select:focus-visible,input:focus-visible,summary:focus-visible,.phone:focus-visible,a:focus-visible{outline:3px solid var(--accent);outline-offset:3px}
::selection{background:var(--accent);color:var(--panel)}
a{color:var(--accent);text-decoration-thickness:from-font;text-underline-offset:.2em}
button:active:not(:disabled){transform:translateY(1px)}
main{max-width:1480px;margin:0 auto;padding:28px 40px 24px}
body[data-rule]{overflow:hidden}
.presentation{width:100%;max-width:none;height:100vh;height:100dvh;padding:12px 24px;display:grid;grid-template-rows:auto minmax(0,1fr) auto;gap:12px;overflow:hidden}
.app-header{display:grid;grid-template-columns:auto auto 1fr;align-items:center;gap:16px;position:relative;z-index:10;background:var(--bg);padding-bottom:12px;border-bottom:1px solid var(--border)}
.rule-nav{display:flex;gap:8px;min-height:44px}
.rule-nav a{display:flex;align-items:center;min-height:44px;padding:8px 16px;border:1px solid var(--control-border);border-radius:8px;text-decoration:none;color:var(--muted)}
.rule-nav a[aria-current="page"]{color:var(--accent);background:var(--selected);border-color:var(--accent)}
.scene-control select{min-width:92px}
.app-header .header-actions{justify-self:end;flex-direction:row}
.sr-only{position:absolute;width:1px;height:1px;padding:0;margin:-1px;overflow:hidden;clip-path:inset(50%);white-space:nowrap;border:0}
.settings{position:static}
.settings>summary{list-style:none;display:flex;align-items:center;min-height:44px;padding:10px 14px;border-radius:8px;cursor:pointer;font-size:14px}
.settings>summary::-webkit-details-marker{display:none}
.settings[open]>summary{color:var(--accent);background:var(--selected)}
.settings-panel{position:absolute;right:0;top:calc(100% + 8px);width:min(280px,calc(100vw - 32px));max-height:calc(100dvh - 140px);overflow:auto;display:grid;gap:12px;padding:16px;border:1px solid var(--border);border-radius:12px;background:var(--panel);box-shadow:0 12px 32px oklch(0 0 0 / .25)}
.settings-panel label{display:flex;align-items:center;justify-content:space-between;gap:12px;min-height:44px}
.settings-panel select{max-width:140px}.settings-panel input{accent-color:var(--accent)}.settings-panel input[type=checkbox]{width:20px;height:20px}
.heading{display:flex;justify-content:space-between;align-items:center;gap:24px;margin-bottom:20px;background:var(--header);border-radius:8px;padding:20px 24px}
.eyebrow{font:600 12px/1.5 var(--font);letter-spacing:1.5px;color:var(--soft-cyan)}
.heading .eyebrow{color:var(--ink)}
h1{font-size:30px;font-weight:600;letter-spacing:-.6px;margin:8px 0}
p{line-height:1.75}.heading p{color:var(--ink);margin:0}
.header-actions{display:flex;gap:8px;flex-shrink:0}
.toolbar{display:flex;align-items:center;gap:20px;border-top:1px solid var(--border);padding:16px 0;flex-wrap:wrap}
.toolbar label{display:flex;align-items:center;gap:8px;font-size:12px;color:var(--muted)}.toolbar select{font-size:14px}
.check{margin-left:auto;min-height:44px}.check input{accent-color:var(--accent);width:18px;height:18px}
.workspace{display:grid;grid-template-columns:minmax(0,1fr) 280px;gap:24px;min-height:0;overflow:hidden}
.stage{background:var(--panel);border-radius:16px;padding:12px;min-width:0;min-height:0;display:grid;place-items:center;overflow:hidden;color:var(--ink)}
.stage-label{display:flex;justify-content:space-between;font-size:12px;color:var(--muted);margin-bottom:16px}
#diagramWrap{position:relative;margin:auto}#diagram{position:absolute;width:640px;height:844px;transform-origin:top left}
.phone{position:absolute;left:0;top:0;width:390px;height:844px;border-radius:55px;background:var(--media-white);overflow:hidden;box-shadow:0 20px 48px oklch(0 0 0 / .2);touch-action:none;user-select:none;cursor:grab}
.phone:active{cursor:grabbing}
.screen-head,.screen-bottom{position:absolute;left:0;width:390px;display:block;z-index:3;pointer-events:none}
.screen-head{top:0;height:91px;overflow:hidden}.screen-bottom{bottom:0;height:83px}
.screen-head img,.feed-chrome img{position:absolute;left:0;top:0;width:390px;height:179px;display:block;pointer-events:none}
.feed{position:absolute;top:91px;bottom:83px;left:0;right:0;overflow:hidden;background:var(--media-white)}
.feed-chrome{position:absolute;left:0;top:0;width:390px;height:88px;overflow:hidden;pointer-events:none}
.feed-chrome img{top:-91px}
.tile{position:absolute;width:187.5px;background:var(--media-white);border-radius:8px;overflow:hidden}
.media{position:relative;width:187.5px;overflow:hidden;border-radius:8px;background:var(--media-gray)}
.cover,.slide,.motion-clip{position:absolute;inset:0;width:100%;height:100%;object-fit:cover;display:block}
.cover{z-index:0}.slide{opacity:0;z-index:1;pointer-events:none}
.motion-clip{opacity:0;z-index:1;pointer-events:none}.motion-clip.visible{opacity:1}
.caption{width:187.5px;display:block;pointer-events:none}
.frame-count{position:absolute;left:8px;top:8px;z-index:3;font:500 10px/1.5 var(--font);font-variant-numeric:tabular-nums;color:var(--media-white);background:var(--scrim);border-radius:8px;padding:0 5px;pointer-events:none}.frame-count:empty{display:none}
.media-progress{position:absolute;bottom:0;left:0;width:100%;height:2px;background:var(--media-white);z-index:3;transform-origin:left;pointer-events:none}
.photo-icon,.sound-icon,.spinner{position:absolute;z-index:3;color:var(--media-white);pointer-events:none}
.photo-icon{width:20px;height:24px;right:6px;top:5px;display:block}
.sound-icon{width:20px;height:20px;right:8px;bottom:8px;display:none}
.sound-icon svg{width:100%;height:100%;display:block}
.spinner{width:18px;height:18px;right:9px;bottom:9px;border:1.7px solid var(--media-white);border-right-color:transparent;border-radius:50%;display:none;animation:spin .8s linear infinite}
.tile[data-status="playing"] .sound-icon{display:block}
.audio-muted .sound-icon:after{content:"";position:absolute;left:9px;top:0;height:21px;border-left:1.5px solid var(--media-white);transform:rotate(-45deg)}
.tile[data-status="loading"] .spinner{display:block}
.media-paused .spinner{animation-play-state:paused}
@keyframes spin{to{transform:rotate(360deg)}}
#activeEdge{position:absolute;width:187.5px;border-top:3px solid var(--accent);z-index:4;pointer-events:none}
#activeEdge span{position:absolute;left:0;top:5px;background:var(--panel);color:var(--accent);font:600 11px/1.5 var(--font);padding:1px 5px;border-radius:3px}
.rule{position:absolute;width:544px;left:0;border-top:1px dashed var(--line);z-index:4;pointer-events:none}
.rule b{position:absolute;left:410px;top:-13px;background:var(--panel);color:var(--line-label);font:600 18px/1.2 var(--font);padding:2px 8px}
.rule i{font:12px/1.5 var(--font);position:absolute;top:12px;left:418px;color:var(--soft-cyan);font-style:normal;white-space:nowrap}
.measure{position:absolute;left:562px;width:1px;border-left:1px solid currentColor;color:var(--accent)}
.measure:nth-child(2){color:var(--line-label)}
.measure.first-measure{left:486px}
.measure:before,.measure:after{content:"";position:absolute;left:-5px;width:10px;border-top:1px solid currentColor}.measure:before{top:0}.measure:after{bottom:0}
.measure span{position:absolute;left:12px;top:50%;transform:translateY(-50%);white-space:nowrap;font:13px/1.5 var(--font);font-variant-numeric:tabular-nums}
.stage-foot{font-size:12px;color:var(--muted);margin:14px 0 0;line-height:1.6}
.explanation{padding:12px 8px 16px 0;min-height:0;overflow:auto}
.now-playing{display:flex;gap:12px;align-items:baseline;color:var(--muted);font-size:12px}.now-playing strong{font-size:28px;font-weight:600;color:var(--accent)}
.explanation h1{font-size:20px;margin:24px 0 16px;letter-spacing:0}
.rule-copy{margin:0;padding-left:24px;display:grid;gap:16px;color:var(--muted);font-size:14px;line-height:1.7}
.rule-copy li[aria-current=step]{color:var(--accent)}
.event-detail{font-size:13px;color:var(--soft-cyan);line-height:1.7}
.media-status{color:var(--muted);font-size:12px;margin-top:8px;font-variant-numeric:tabular-nums}
.event-title{font-size:20px;line-height:1.4;margin-top:20px;font-weight:500}
#eventDetail{color:var(--muted);font-size:13px}
dl{border-top:1px solid var(--border);border-bottom:1px solid var(--border);padding:12px 0;margin:16px 0}dl div{display:flex;justify-content:space-between;line-height:2.1}dt{color:var(--muted);font-size:12px}dd{margin:0;font:13px/2.1 var(--font);font-variant-numeric:tabular-nums}
.steps-heading{display:flex;justify-content:space-between;font-size:12px;margin-bottom:8px}.steps-heading span{color:var(--muted)}
.steps{max-height:172px;overflow:auto;display:grid;gap:4px}
.steps button{text-align:left;background:transparent;border-color:transparent;font-size:12px;min-height:44px;padding:8px 12px;display:flex;justify-content:space-between;gap:8px}
.steps button.selected{background:var(--selected);border-color:var(--accent);color:var(--accent)}.steps button span{color:var(--muted);font-family:var(--font);font-variant-numeric:tabular-nums}
details{color:var(--muted);font-size:12px}summary{cursor:pointer;min-height:44px;display:flex;align-items:center}.steps-panel{margin-top:24px;border-top:1px solid var(--border);padding-top:8px}
.transport{display:flex;align-items:center;gap:16px;padding-top:12px;border-top:1px solid var(--border);background:var(--bg);min-width:0;position:relative;z-index:5}
.transport-buttons{display:flex;gap:8px;flex-wrap:wrap}
.primary{background:var(--accent);color:var(--panel);border-color:var(--accent);min-width:108px;font-weight:600}
.timeline{flex:1;font-size:11px;color:var(--muted);display:flex;gap:12px;align-items:center;white-space:nowrap}.timeline input{width:100%;accent-color:var(--accent);min-height:44px}
output{font:12px/1.5 var(--font);font-variant-numeric:tabular-nums;min-width:40px}.materials{display:flex;gap:24px;margin-top:16px;font-size:12px;line-height:1.8}.materials strong{white-space:nowrap}.materials span{color:var(--muted)}
.audio-controls{display:flex;align-items:center;gap:16px;flex-wrap:wrap;margin-top:16px}.audio-controls label{display:flex;align-items:center;gap:8px;font-size:12px;color:var(--muted)}.audio-controls input{accent-color:var(--accent);min-height:44px;width:120px}.audio-controls>span{color:var(--muted);font-size:12px}
table{width:100%;border-collapse:collapse;font-variant-numeric:tabular-nums}th{text-align:left;background:var(--header);color:var(--ink);font-weight:600}th,td{border-bottom:1px solid var(--border)}td{color:var(--muted)}tbody tr:nth-child(even){background:var(--panel)}
main:fullscreen{background:var(--bg);max-width:none}
.presentation:fullscreen{height:100vh;height:100dvh;overflow:hidden}
[hidden]{display:none!important}
@media(hover:hover){button:hover:not(:disabled){background:var(--hover)}.primary:hover:not(:disabled){background:var(--soft-cyan)}.steps button.selected:hover{background:var(--selected)}a:hover{color:var(--soft-cyan)}}
@media(max-width:1100px){main{padding:24px}.workspace{grid-template-columns:minmax(360px,1fr) 260px;gap:20px}.check{margin-left:0}.heading{align-items:flex-start}.header-actions{flex-direction:column}.stage{padding:16px}.transport{flex-wrap:wrap}.timeline{min-width:200px}}
@media(max-width:760px){main{padding:24px 16px}.workspace{grid-template-columns:1fr}.heading{display:block;padding:20px 16px}.header-actions{flex-direction:row;margin-top:16px}h1{font-size:26px}.stage-label{font-size:10px}.active-name{font-size:40px}.toolbar{gap:12px}.toolbar label{flex-wrap:wrap}.toolbar select,input{font-size:16px}.materials{display:block}.materials strong{display:block;margin-bottom:8px}.transport-buttons{width:100%}.transport-buttons button{padding:10px 12px}.event-title{margin-top:12px}#eventDetail{min-height:0}}
/* Viewport shell stays fixed; only the workspace and side notes scroll. */
@media(max-width:1100px){
  .presentation{padding:12px 16px}
  .workspace{grid-template-columns:minmax(0,1fr) 248px;gap:16px}
  .stage{padding:12px}
  .app-header .header-actions{margin:0;flex-direction:row}
  .transport{flex-wrap:wrap;gap:8px 12px}
  .transport-buttons{width:100%}
  .timeline{min-width:0}
}
@media(max-width:760px){
  .presentation{padding:8px 12px max(8px,env(safe-area-inset-bottom));gap:8px}
  .workspace{grid-template-columns:minmax(0,1fr);grid-template-rows:auto auto;align-content:start;gap:12px;overflow:auto}
  .stage{overflow:hidden}
  .explanation{overflow:visible;padding:8px 12px 16px}
  .explanation h1{margin-top:16px}
  .rule-copy{gap:12px}
  .app-header{gap:8px;padding-bottom:8px}
  .app-header .header-actions{margin:0}
  .rule-nav{gap:4px}
  .rule-nav a{padding:8px 12px;white-space:nowrap}
  .transport{padding-top:8px}
  .transport-buttons{display:grid;grid-template-columns:repeat(5,minmax(0,1fr));gap:6px}
  .transport-buttons button{min-width:0;padding:8px 4px;font-size:12px}
}
@media(max-width:560px){
  .app-header{grid-template-columns:1fr auto}
  .rule-nav{grid-column:1/-1}
  .scene-control{grid-column:1}
  .app-header .header-actions{grid-column:2}
  .transport-buttons{grid-template-columns:repeat(3,minmax(0,1fr))}
  .scene-control select{font-size:16px}
}
@media(prefers-reduced-motion:reduce){*,*:before,*:after{scroll-behavior:auto!important}.slide{transition:none}.spinner{animation:none}.media-progress{display:none}}