:root{
  --bg:#f5f5f7; --card:#fff; --ink:#1d1d2b; --muted:#6b6b80; --line:#e3e3ea;
  --accent:#5b4cf0; --accent-ink:#fff; --ok:#12a150; --bad:#e5484d;
  --c0:#5b4cf0; --c1:#f0584c; --c2:#1fa37a; --c3:#f2a516; --c4:#2d9cdb; --c5:#c44fd6; --c6:#6d7c8f; --c7:#e36ea6;
  --radius:14px;
}
*{box-sizing:border-box}
html,body{margin:0;padding:0}
body{font-family:system-ui,-apple-system,"Segoe UI",Roboto,"Helvetica Neue",Arial,sans-serif;background:var(--bg);color:var(--ink);-webkit-font-smoothing:antialiased}
button{font:inherit;cursor:pointer}
input,textarea,select{font:inherit}
.hidden{display:none!important}

/* ---------------- student ---------------- */
.play{min-height:100vh;min-height:100dvh;display:flex;flex-direction:column}
.play header{padding:14px 16px;display:flex;justify-content:space-between;align-items:center;font-weight:700;color:var(--muted);font-size:14px}
.play header .brand{color:var(--accent);letter-spacing:.02em}
.play main{flex:1;display:flex;flex-direction:column;justify-content:center;padding:16px;max-width:560px;width:100%;margin:0 auto}
.play h1{font-size:26px;line-height:1.25;margin:0 0 20px}
.play .sub{color:var(--muted);margin:-10px 0 20px}
.field{width:100%;padding:16px;font-size:20px;border:2px solid var(--line);border-radius:var(--radius);background:#fff;color:var(--ink);outline:none}
.field:focus{border-color:var(--accent)}
.field.code{text-align:center;font-size:32px;letter-spacing:.2em;font-weight:700}
.btn{display:block;width:100%;padding:16px;border:0;border-radius:var(--radius);background:var(--accent);color:var(--accent-ink);font-size:18px;font-weight:700;margin-top:12px}
.btn:disabled{opacity:.5}
.btn.ghost{background:transparent;color:var(--accent);border:2px solid var(--accent)}
.err{color:var(--bad);margin-top:12px;min-height:1.2em}
.opts{display:flex;flex-direction:column;gap:10px}
.opt{display:flex;align-items:center;gap:14px;width:100%;text-align:left;padding:16px;border:2px solid var(--line);border-radius:var(--radius);background:#fff;font-size:18px;color:var(--ink);transition:transform .08s}
.opt:active{transform:scale(.98)}
.opt .let{flex:none;width:36px;height:36px;border-radius:10px;display:grid;place-items:center;color:#fff;font-weight:800}
.opt.sel{border-color:var(--accent);background:#efedff}
.opt.right{border-color:var(--ok);background:#e6f6ec}
.opt.wrongsel{border-color:var(--bad);background:#fdeaea}
.scale{display:grid;grid-template-columns:repeat(auto-fit,minmax(48px,1fr));gap:8px}
.scale button{padding:16px 0;border:2px solid var(--line);border-radius:12px;background:#fff;font-size:20px;font-weight:700;color:var(--ink)}
.scale-labels{display:flex;justify-content:space-between;color:var(--muted);font-size:14px;margin-top:8px;gap:12px}
.center{text-align:center}
.big-emoji{font-size:64px;line-height:1;margin-bottom:10px}
.status{font-size:24px;font-weight:700;margin:0 0 8px}
.muted{color:var(--muted)}
.pill{display:inline-block;padding:6px 12px;border-radius:999px;background:#ecebfb;color:var(--accent);font-weight:700;font-size:14px}
.result{border-radius:var(--radius);padding:24px;color:#fff;text-align:center}
.result.ok{background:var(--ok)} .result.no{background:var(--bad)} .result.none{background:var(--muted)}
.result h2{margin:0 0 6px;font-size:30px}
.scorebox{margin-top:16px;background:#fff;border-radius:var(--radius);padding:16px;display:flex;justify-content:space-around;text-align:center}
.scorebox b{display:block;font-size:26px}
.expl{margin-top:16px;background:#fff;border-left:4px solid var(--accent);border-radius:10px;padding:14px 16px;line-height:1.45}
.timer{font-variant-numeric:tabular-nums;font-weight:800;color:var(--accent)}
.timer.low{color:var(--bad)}
.qimg{max-width:100%;max-height:220px;border-radius:12px;margin:0 0 16px;display:block}
.sent-list{margin:12px 0 0;padding:0;list-style:none;display:flex;flex-wrap:wrap;gap:8px}
.sent-list li{background:#ecebfb;color:var(--accent);padding:6px 12px;border-radius:999px;font-weight:600}
.net{position:fixed;left:0;right:0;bottom:0;background:#333;color:#fff;text-align:center;padding:8px;font-size:14px}

/* ---------------- presenter ---------------- */
.pres{height:100vh;height:100dvh;display:flex;flex-direction:column;overflow:hidden;background:#fff}
.pres .top{display:flex;justify-content:space-between;align-items:center;padding:14px 28px;font-size:18px;color:var(--muted)}
.pres .top .join b{color:var(--ink);font-size:22px}
.pres .top .join .c{color:var(--accent);letter-spacing:.06em}
.pres .top .stats{display:flex;gap:22px;align-items:center}
.pres .top .stats span b{color:var(--ink)}
.stage{flex:1;display:flex;flex-direction:column;padding:10px 6vw 90px;min-height:0}
.stage h1{font-size:clamp(28px,4vw,56px);line-height:1.15;margin:2vh 0 3vh;font-weight:800}
.stage .qn{color:var(--muted);font-weight:700;font-size:18px;text-transform:uppercase;letter-spacing:.08em}
.bars{flex:1;display:flex;align-items:flex-end;gap:3vw;min-height:0;padding-bottom:8px}
.bar{flex:1;display:flex;flex-direction:column;justify-content:flex-end;height:100%;min-width:0}
.bar .track{flex:1;min-height:0;display:flex;flex-direction:column;justify-content:flex-end}
.bar .val{text-align:center;font-weight:800;font-size:clamp(18px,2.2vw,34px);margin-bottom:6px}
.bar .fill{border-radius:10px 10px 0 0;min-height:6px;transition:height .6s cubic-bezier(.2,.8,.2,1),opacity .4s}
.bar .lab{border-top:3px solid var(--ink);padding-top:10px;text-align:center;font-size:clamp(14px,1.6vw,24px);font-weight:600;line-height:1.2;min-height:3.2em;word-break:break-word}
.bar .lab .let{display:inline-block;width:1.5em;height:1.5em;line-height:1.5em;border-radius:6px;color:#fff;font-weight:800;margin-right:6px;font-size:.85em}
.bar.dim .fill{opacity:.25} .bar.dim .lab{opacity:.45}
.bar.win .lab{color:var(--ok)}
.bar.win .lab::after{content:" ✓";font-weight:900}
.hidden-note{color:var(--muted);font-size:20px;text-align:center;margin-top:10px}
.cloud{flex:1;display:flex;flex-wrap:wrap;justify-content:center;align-content:center;gap:.3em 1em;padding:2vh 0;overflow:hidden}
.cloud span{font-weight:800;line-height:1.1;transition:font-size .5s}
.cards{flex:1;display:grid;grid-template-columns:repeat(auto-fill,minmax(260px,1fr));gap:14px;overflow:auto;align-content:start}
.cards div{background:#f3f2ff;border-radius:12px;padding:16px 18px;font-size:20px;line-height:1.35;animation:pop .35s ease}
@keyframes pop{from{transform:scale(.9);opacity:0}to{transform:none;opacity:1}}
.avg{font-size:clamp(40px,6vw,90px);font-weight:900;color:var(--accent);line-height:1}
.avg small{font-size:.3em;color:var(--muted);font-weight:700;display:block;margin-top:6px}
.scale-wrap{flex:1;display:flex;gap:4vw;align-items:stretch;min-height:0}
.scale-wrap .bars{flex:1}
.slide-body{font-size:clamp(20px,2.4vw,36px);line-height:1.45;white-space:pre-wrap;color:#333}
.lobby{flex:1;display:flex;align-items:center;justify-content:center;gap:6vw}
.lobby .how{font-size:clamp(22px,2.6vw,40px);line-height:1.4}
.lobby .how .url{color:var(--ink);font-weight:800}
.lobby .how .code{display:block;font-size:clamp(60px,10vw,150px);font-weight:900;color:var(--accent);letter-spacing:.06em;line-height:1.05}
.lobby .qr{background:#fff;padding:18px;border-radius:16px;box-shadow:0 4px 30px rgba(0,0,0,.08);width:min(32vw,340px)}
.lobby .qr svg{display:block;width:100%;height:auto}
.lobby .count{margin-top:18px;font-size:22px;color:var(--muted)}
.lobby .count b{color:var(--ink);font-size:32px}
.lb{flex:1;display:flex;flex-direction:column;gap:10px;max-width:900px;width:100%;margin:0 auto;overflow:auto}
.lb .row{display:flex;align-items:center;gap:18px;background:#f5f5fb;border-radius:12px;padding:12px 20px;font-size:clamp(18px,2vw,28px);animation:pop .4s ease both}
.lb .row .r{width:2em;font-weight:900;color:var(--muted)}
.lb .row .n{flex:1;font-weight:700;overflow:hidden;text-overflow:ellipsis;white-space:nowrap}
.lb .row .s{font-weight:800;font-variant-numeric:tabular-nums}
.lb .row.p1{background:#fff4d6} .lb .row.p1 .r{color:#c98a00}
.lb .row.p2{background:#eef0f4} .lb .row.p3{background:#fbeee4}
.expl-p{margin-top:12px;font-size:clamp(16px,1.7vw,24px);background:#f3f2ff;border-left:6px solid var(--accent);padding:12px 18px;border-radius:10px}
.pct{color:var(--ok);font-weight:800}
.ctrl{position:fixed;left:50%;bottom:16px;transform:translateX(-50%);display:flex;gap:8px;background:rgba(29,29,43,.92);padding:8px;border-radius:14px;transition:opacity .3s;z-index:5;align-items:center}
.ctrl button,.ctrl select{white-space:nowrap;border:0;background:transparent;color:#fff;padding:10px 14px;border-radius:10px;font-weight:600;font-size:15px}
.ctrl select{background:#2c2c3e;max-width:180px}
.ctrl button:hover{background:rgba(255,255,255,.12)}
.ctrl button.primary{background:var(--accent)}
.ctrl.idle{opacity:0}
.ptimer{font-size:28px;font-weight:900;color:var(--accent);font-variant-numeric:tabular-nums}
.ptimer.low{color:var(--bad)}
.corner{position:fixed;right:24px;bottom:22px;color:var(--muted);font-size:16px}
.corner b{color:var(--accent)}

/* ---------------- admin ---------------- */
.admin{max-width:1100px;margin:0 auto;padding:24px 16px 60px}
.admin h1{margin:0 0 4px}
.admin .card{background:#fff;border-radius:var(--radius);padding:20px;margin:18px 0;box-shadow:0 1px 3px rgba(0,0,0,.05)}
.admin table{width:100%;border-collapse:collapse}
.admin th,.admin td{text-align:left;padding:10px 8px;border-bottom:1px solid var(--line);vertical-align:top}
.admin th{font-size:13px;text-transform:uppercase;color:var(--muted);letter-spacing:.04em}
.admin a{color:var(--accent)}
.admin .actions{display:flex;flex-wrap:wrap;gap:6px}
.admin .actions a,.admin .actions button,.abtn{display:inline-block;padding:6px 10px;border-radius:8px;background:#efedff;color:var(--accent);text-decoration:none;font-weight:600;font-size:14px;border:0}
.admin .actions .danger,.abtn.danger{background:#fdeaea;color:var(--bad)}
.abtn.primary{background:var(--accent);color:#fff;padding:10px 16px}
.admin textarea{width:100%;min-height:260px;font-family:ui-monospace,Menlo,Consolas,monospace;font-size:13px;padding:12px;border:1px solid var(--line);border-radius:10px}
.admin code{background:#f0f0f5;padding:2px 6px;border-radius:6px;font-size:13px;word-break:break-all}
.admin .msg{padding:12px 14px;border-radius:10px;background:#e6f6ec;color:#0b6b35;margin:12px 0}
.admin .msg.bad{background:#fdeaea;color:#a1161b}
.admin .tbl-wrap{overflow-x:auto}
.minibar{height:10px;background:var(--accent);border-radius:4px;display:inline-block;vertical-align:middle;margin-right:8px}
.admin .qres{border-top:1px solid var(--line);padding:14px 0}
.admin .okc{color:var(--ok);font-weight:700}
.admin .badc{color:var(--bad)}
@media (max-width:700px){
  .lobby{flex-direction:column;gap:20px}
  .pres .top{padding:10px 14px;font-size:14px}
  .stage{padding:8px 16px 90px}
  .ctrl{bottom:8px;max-width:calc(100vw - 16px);overflow-x:auto}
}