:root{
  --bg:#0d1117; --panel:#161b22; --line:#2d333b;
  --ink:#e6edf3; --dim:#8b949e;
  --hot:#ff6b35;      /* pressure / timer / wrong */
  --good:#3fb950;     /* correct / reward */
  --cool:#58a6ff;     /* neutral accent, numbers */
  --mono:ui-monospace,SFMono-Regular,Menlo,monospace;
}
*{box-sizing:border-box;-webkit-tap-highlight-color:transparent}
html,body{margin:0;height:100%}
body{
  background:var(--bg);color:var(--ink);
  font:16px/1.45 -apple-system,BlinkMacSystemFont,"Segoe UI",system-ui,sans-serif;
  display:flex;justify-content:center;
  padding:env(safe-area-inset-top) 0 env(safe-area-inset-bottom);
  overscroll-behavior:none;
}
.app{width:100%;max-width:430px;display:flex;flex-direction:column;min-height:100dvh;padding:14px}
.num{font-family:var(--mono);font-variant-numeric:tabular-nums}
h1{font-size:19px;margin:0;letter-spacing:.02em}
.sub{color:var(--dim);font-size:13px;margin:2px 0 0}
.top{display:flex;justify-content:space-between;align-items:flex-start;gap:10px;margin-bottom:12px}
.clock{font-family:var(--mono);font-size:15px;color:var(--dim)}
.clock.warn{color:var(--hot)}
.bar{height:3px;background:var(--line);border-radius:2px;overflow:hidden;margin-bottom:14px}
.bar>i{display:block;height:100%;background:var(--cool);transition:width .2s linear}
.bar.warn>i{background:var(--hot)}
.stage{flex:1;display:flex;flex-direction:column;justify-content:space-between;gap:14px;padding:6px 0 2px}
.stage>*{flex:0 0 auto}
.stage>.stem{flex:1 1 auto;margin:0}
.stem{font-size:27px;font-family:var(--mono);text-align:center;line-height:1.35;min-height:2.4em;
      display:flex;align-items:center;justify-content:center;padding:0 6px}
.choices{display:grid;grid-template-columns:1fr 1fr;gap:9px}
.ch{background:var(--panel);border:1px solid var(--line);color:var(--ink);
    border-radius:11px;padding:17px 8px;font-size:19px;font-family:var(--mono);
    cursor:pointer;transition:transform .07s,background .12s,border-color .12s}
.ch:active{transform:scale(.97)}
.ch.right{background:rgba(63,185,80,.16);border-color:var(--good);color:var(--good)}
.ch.wrong{background:rgba(255,107,53,.14);border-color:var(--hot);color:var(--hot)}
.ch:disabled{cursor:default}
.btn{background:var(--cool);color:#06121f;border:0;border-radius:11px;padding:15px;
     font-size:16px;font-weight:640;cursor:pointer;width:100%;font-family:inherit}
.btn.ghost{background:transparent;color:var(--dim);border:1px solid var(--line)}
.row{display:flex;gap:9px}
.card{background:var(--panel);border:1px solid var(--line);border-radius:13px;padding:15px}
.big{font-size:52px;font-family:var(--mono);line-height:1;font-variant-numeric:tabular-nums}
.dim{color:var(--dim)}.hot{color:var(--hot)}.good{color:var(--good)}.cool{color:var(--cool)}
.center{text-align:center}
.pop{animation:pop .32s cubic-bezier(.2,1.6,.4,1)}
@keyframes pop{0%{transform:scale(.82);opacity:.4}100%{transform:scale(1);opacity:1}}
.shake{animation:shake .3s}
@keyframes shake{0%,100%{transform:translateX(0)}25%{transform:translateX(-6px)}75%{transform:translateX(6px)}}
.rise{animation:rise .5s ease-out}
@keyframes rise{from{transform:translateY(9px);opacity:0}to{transform:translateY(0);opacity:1}}
pre.log{font-family:var(--mono);font-size:10px;color:var(--dim);background:#010409;
        border:1px solid var(--line);border-radius:8px;padding:9px;max-height:130px;overflow:auto;
        white-space:pre-wrap;word-break:break-all}
a.back{color:var(--dim);font-size:13px;text-decoration:none}