/* Layout: one narrow column for intro / done; a question puts the control video on the left (sticky)
   and the four candidates in a 2x2 grid on the right; everything stacks to one column on phones.
   System fonts only: Google Fonts is unreachable from mainland China and would stall the page. */
:root{
  --bg:#f3f5f8; --surface:#ffffff; --ink:#141922; --muted:#5a6373; --line:#d8dde6;
  --accent:#2a52d4; --accent-ink:#ffffff; --accent-soft:#e5ebfc;
  --frame:#0d1015; --frame-ink:#b9c2d0; --frame-grid:#1b212b;
  --demo-obj:#e0a33a; --demo-part:#4fb6c9;
  --ok:#17724a; --warn:#9a5208;
  --f-body:-apple-system,BlinkMacSystemFont,"PingFang SC","Hiragino Sans GB","Microsoft YaHei","Segoe UI",Roboto,"Noto Sans SC",sans-serif;
  --f-mono:ui-monospace,"SF Mono",Menlo,Consolas,"Roboto Mono",monospace;
  --r:12px;
  color-scheme:light;
}
@media (prefers-color-scheme: dark){
  :root{
    --bg:#0e1116; --surface:#161a21; --ink:#e6e9ef; --muted:#97a0ae; --line:#2a313c;
    --accent:#86a2ff; --accent-ink:#0a0f1d; --accent-soft:#1c2541;
    --frame:#05070a; --frame-ink:#a9b2c1; --frame-grid:#141922;
    --ok:#5cc792; --warn:#e3a25a; color-scheme:dark;
  }
}
*{box-sizing:border-box}
[hidden]{display:none!important}
html{-webkit-text-size-adjust:100%}
body{margin:0;background:var(--bg);color:var(--ink);font-family:var(--f-body);font-size:16px;line-height:1.6}
.wrap{max-width:1240px;margin:0 auto;padding-left:max(16px,env(safe-area-inset-left,0px));padding-right:max(16px,env(safe-area-inset-right,0px));padding-block:max(16px,env(safe-area-inset-top,0px)) 56px}
h1,h2,h3{font-weight:700;line-height:1.25;margin:0;text-wrap:balance}
h1{font-size:28px} h2{font-size:20px}
p{margin:0}
button{font:inherit;color:inherit}
:focus-visible{outline:3px solid var(--accent);outline-offset:2px}

.top{display:flex;align-items:center;justify-content:space-between;gap:12px;flex-wrap:wrap;padding-bottom:12px;border-bottom:1px solid var(--line);margin-bottom:20px}
.brand{font-weight:700;font-size:17px;min-width:0}
.ghost{border:1px solid var(--line);background:var(--surface);border-radius:10px;padding:8px 14px;cursor:pointer;font-size:15px;min-height:44px}
.ghost:hover{border-color:var(--muted)}
.ghost[aria-pressed="true"]{background:var(--accent-soft);border-color:var(--accent)}

.btn{appearance:none;border:1px solid var(--line);background:var(--surface);border-radius:12px;padding:12px 22px;cursor:pointer;font-weight:600;font-size:17px;min-height:52px}
.btn:hover:not(:disabled){border-color:var(--muted)}
.btn.primary{background:var(--accent);border-color:var(--accent);color:var(--accent-ink)}
.btn:disabled{opacity:.4;cursor:not-allowed}
.btn.quiet{border-color:transparent;background:transparent;color:var(--muted);font-weight:500;font-size:15px}

.note{border:1px solid var(--line);background:var(--surface);border-radius:10px;padding:10px 14px;font-size:15px;color:var(--muted)}
.note.warn{border-color:var(--warn);color:var(--ink)}
.note b{color:var(--ink)}
.col{max-width:640px;display:flex;flex-direction:column;gap:20px}
.lead{font-size:18px}
.steps{display:flex;flex-direction:column;gap:10px;margin:0;padding:0;list-style:none;font-size:17px}
.steps li{display:flex;gap:12px;align-items:baseline}
.steps .n{flex:none;width:28px;height:28px;border-radius:50%;background:var(--accent-soft);color:var(--ink);display:inline-grid;place-items:center;font-weight:700;font-size:15px}
.field{display:flex;flex-direction:column;gap:6px}
.field label{font-size:16px;font-weight:600}
.field input{border:1px solid var(--line);background:var(--surface);color:var(--ink);border-radius:10px;padding:12px 14px;font:inherit;font-size:17px;max-width:360px;width:100%}
.row{display:flex;gap:12px;flex-wrap:wrap;align-items:center}
.meta{font-size:14px;color:var(--muted)}

.qhead{display:flex;align-items:center;gap:14px;flex-wrap:wrap;margin-bottom:14px}
.qcount{font-weight:700;font-size:17px;font-variant-numeric:tabular-nums;white-space:nowrap}
.bar{flex:1 1 160px;height:6px;background:var(--line);border-radius:6px;overflow:hidden;min-width:120px}
.bar > i{display:block;height:100%;background:var(--accent);border-radius:6px}
.qtitle{font-size:19px;width:100%}
.stage{display:grid;grid-template-columns:minmax(0,5fr) minmax(0,7fr);gap:22px;align-items:start}
.ctrl-col{position:sticky;top:12px;display:flex;flex-direction:column;gap:10px;min-width:0}
.cand-col{display:flex;flex-direction:column;gap:12px;min-width:0}
.label{font-size:14px;font-weight:600;color:var(--muted)}
.ctrl-card{background:var(--surface);border:1px solid var(--line);border-radius:var(--r);padding:8px;display:flex;flex-direction:column;gap:8px}
.frame{position:relative;aspect-ratio:16/9;max-width:100%;background:var(--frame);border-radius:8px;overflow:hidden}
.frame video,.frame canvas{position:absolute;inset:0;width:100%;height:100%;display:block;object-fit:contain}
.vid-err{position:absolute;inset:0;display:grid;place-items:center;color:var(--frame-ink);font-size:14px;padding:10px;text-align:center}
.player{display:flex;align-items:center;gap:8px;flex-wrap:wrap}
.scrub{flex:1 1 140px;min-width:0;accent-color:var(--accent);height:28px}
.time{font-family:var(--f-mono);font-size:13px;font-variant-numeric:tabular-nums;color:var(--muted);white-space:nowrap}
.grid{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:12px}
.cand{appearance:none;display:block;width:100%;text-align:left;cursor:pointer;background:var(--surface);border:3px solid var(--line);border-radius:var(--r);padding:6px;position:relative}
.cand:hover{border-color:var(--muted)}
.cand[aria-checked="true"]{border-color:var(--accent);box-shadow:0 0 0 3px var(--accent-soft)}
.badge{position:absolute;top:12px;left:12px;z-index:2;font-weight:800;font-size:16px;width:32px;height:32px;display:grid;place-items:center;border-radius:8px;background:var(--surface);color:var(--ink);border:1px solid var(--line)}
.cand[aria-checked="true"] .badge,.allsame[aria-checked="true"] .badge{background:var(--accent);color:var(--accent-ink);border-color:var(--accent)}
.tick{position:absolute;top:12px;right:12px;z-index:2;font-size:14px;font-weight:700;padding:4px 10px;border-radius:8px;background:var(--accent);color:var(--accent-ink)}
.allsame{appearance:none;width:100%;cursor:pointer;background:var(--surface);border:3px solid var(--line);border-radius:var(--r);padding:14px 16px;display:flex;align-items:center;gap:14px;text-align:left;min-height:64px}
.allsame:hover{border-color:var(--muted)}
.allsame[aria-checked="true"]{border-color:var(--accent);box-shadow:0 0 0 3px var(--accent-soft)}
.allsame .badge{position:static;flex:none}
.allsame b{font-size:17px}
.allsame small{display:block;color:var(--muted);font-size:14px}
.qnav{display:flex;align-items:center;justify-content:space-between;gap:12px;flex-wrap:wrap;margin-top:22px;padding-top:16px;border-top:1px solid var(--line)}
.keys{font-size:13px;color:var(--muted)}
.keys kbd{font-family:var(--f-mono);font-size:12px;border:1px solid var(--line);border-bottom-width:2px;border-radius:4px;padding:0 5px;background:var(--surface)}
@media (hover: none){ .keys{display:none} }
.status{display:inline-flex;align-items:center;gap:10px;font-weight:700;font-size:22px}
.dot{width:12px;height:12px;border-radius:50%;background:var(--ok);flex:none}
.dot.warn{background:var(--warn)}

@media (max-width: 820px){
  .stage{grid-template-columns:minmax(0,1fr)}
  .ctrl-col{position:static}
  .qnav .btn{flex:1 1 0}
}
@media (max-width: 420px){
  h1{font-size:24px}
  .grid{gap:8px}
  .cand{padding:4px}
  .badge{top:8px;left:8px;width:28px;height:28px;font-size:15px}
  .tick{top:8px;right:8px;font-size:13px;padding:3px 8px}
}

/* results page */
.res{display:flex;flex-direction:column;gap:26px;max-width:980px}
.res section{display:flex;flex-direction:column;gap:12px}
.bars{display:grid;grid-template-columns:minmax(90px,max-content) minmax(0,1fr) max-content;gap:8px 12px;align-items:center}
.bars .track{height:14px;background:var(--line);border-radius:3px;overflow:hidden}
.bars .fill{height:100%;background:var(--accent);border-radius:3px}
.bars .fill.alt{background:var(--muted)}
.bars .val{font-family:var(--f-mono);font-size:13px;font-variant-numeric:tabular-nums;color:var(--muted);text-align:right}
.tablebox{overflow-x:auto;border:1px solid var(--line);border-radius:10px;background:var(--surface)}
table{border-collapse:collapse;width:100%;font-size:14px}
th,td{padding:8px 12px;border-bottom:1px solid var(--line);text-align:right;white-space:nowrap;font-variant-numeric:tabular-nums}
th:first-child,td:first-child{text-align:left}
th{font-weight:600;font-size:13px;color:var(--muted)}
tbody tr:last-child td{border-bottom:0}
tr.total td{font-weight:700;border-top:2px solid var(--line)}
td.top{color:var(--accent);font-weight:700}
.people{display:flex;flex-direction:column;border:1px solid var(--line);border-radius:10px;background:var(--surface)}
.people > div{display:flex;gap:12px;align-items:baseline;padding:8px 12px;border-bottom:1px solid var(--line);flex-wrap:wrap}
.people > div:last-child{border-bottom:0}
.people .who{font-weight:600;min-width:0;overflow-wrap:anywhere}
.chip{font-size:12px;border:1px solid var(--line);border-radius:6px;padding:0 7px;color:var(--muted)}
.chip.test{border-color:var(--warn);color:var(--warn)}
.chip.done{border-color:var(--ok);color:var(--ok)}
.check{display:inline-flex;align-items:center;gap:8px;font-size:15px;cursor:pointer}
.paste{width:100%;min-height:80px;resize:vertical;font-family:var(--f-mono);font-size:13px;border:1px solid var(--line);background:var(--surface);color:var(--ink);border-radius:10px;padding:10px 12px}