:root {
  --ink: #1c1917;
  --muted: #78716c;
  --bg: #fafaf9;
  --panel: #ffffff;
  --panel-2: #f5f5f4;
  --line: #e7e5e4;
  --line-strong: #d6d3d1;
  --brand: #0f766e;
  --brand-ink: #ffffff;
  --ok: #15803d;
  --no: #b91c1c;
  --warn: #b45309;
  --body: system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
  color-scheme: light;
}
* { box-sizing: border-box; }
html, body { margin: 0; }
body {
  font: 15px/1.55 var(--body);
  color: var(--ink);
  background: var(--bg);
  padding: env(safe-area-inset-top, 0) 0 env(safe-area-inset-bottom, 0);
}
code { font: 13px/1.4 ui-monospace, "SF Mono", Menlo, Consolas, monospace;
  background: var(--panel-2); border: 1px solid var(--line); border-radius: 4px; padding: 1px 5px; }
.wrap { max-width: 640px; margin: 0 auto; padding: 20px 16px 48px; }
.wide { max-width: 1080px; }
.topbar { display: flex; align-items: center; gap: 10px; padding: 12px 16px;
  border-bottom: 1px solid var(--line); background: var(--panel); position: sticky; top: 0; z-index: 5; }
.topbar b { font-size: 15px; }
.spacer { flex: 1; }
.chip { font-size: 12px; padding: 3px 9px; border-radius: 999px; background: var(--panel-2);
  color: var(--muted); border: 1px solid var(--line); }
.chip.on { background: #ecfdf5; color: var(--brand); border-color: #99f6e4; }
.eyebrow { text-transform: uppercase; letter-spacing: .06em; font-size: 12px; font-weight: 600; color: var(--muted); }
h1 { font-size: 22px; margin: 6px 0 2px; }
h2 { font-size: 16px; margin: 0; }
.lede { color: var(--muted); margin: 8px 0 0; }
.panel { background: var(--panel); border: 1px solid var(--line); border-radius: 10px; padding: 16px; margin-top: 14px; }
.stack > * + * { margin-top: 12px; }
label.fld { display: block; font-weight: 600; font-size: 13px; margin-bottom: 6px; }
input, select { width: 100%; padding: 11px 12px; font: 400 16px var(--body); color: var(--ink);
  background: var(--panel); border: 1px solid var(--line-strong); border-radius: 8px; }
input:focus, select:focus { outline: 2px solid var(--brand); border-color: var(--brand); }
button { font: 600 15px var(--body); cursor: pointer; border-radius: 8px; border: 1px solid var(--line-strong);
  background: var(--panel); color: var(--ink); padding: 11px 14px; }
button.primary { background: var(--brand); color: var(--brand-ink); border-color: var(--brand); width: 100%; }
button.sm { padding: 7px 11px; font-size: 13px; width: auto; }
button.ghost { background: transparent; border-color: transparent; color: var(--muted); }
.row { display: flex; gap: 10px; align-items: center; }
.daygroup { margin-top: 18px; }
.dayhead { display: flex; align-items: baseline; gap: 8px; margin-bottom: 8px; }
.dayhead .sub { color: var(--muted); font-size: 13px; }
.qlist { list-style: none; margin: 0; padding: 0; }
.qitem { display: flex; align-items: center; gap: 12px; padding: 12px 14px; background: var(--panel);
  border: 1px solid var(--line); border-radius: 10px; margin-top: 8px; }
.qitem .jam { font-variant-numeric: tabular-nums; font-weight: 600; color: var(--muted); width: 48px; }
.qitem .nm { flex: 1; }
.qitem .nm small { display: block; color: var(--muted); font-size: 12px; }
.done { font-variant-numeric: tabular-nums; font-weight: 700; color: var(--brand); }
.timer { font-variant-numeric: tabular-nums; font-weight: 700; font-size: 18px; color: var(--ink); }
.timer.low { color: var(--no); }
.qnum { font-size: 13px; color: var(--muted); font-weight: 600; }
.qtext { font-size: 17px; margin: 8px 0 14px; }
.opts { display: grid; gap: 8px; }
.opt { display: flex; gap: 10px; align-items: flex-start; text-align: left; width: 100%;
  padding: 12px; border: 1px solid var(--line-strong); border-radius: 8px; background: var(--panel); }
.opt.pick { border-color: var(--brand); background: #ecfdf5; }
.opt.right { border-color: var(--ok); background: #f0fdf4; }
.opt.wrong { border-color: var(--no); background: #fef2f2; }
.opt .ltr { font-weight: 700; color: var(--muted); min-width: 18px; }
.score { font-size: 44px; font-weight: 800; line-height: 1; }
.score small { font-size: 18px; color: var(--muted); font-weight: 600; }
.verdict { font-size: 12px; font-weight: 700; padding: 2px 8px; border-radius: 999px; }
.verdict.ok { background: #f0fdf4; color: var(--ok); }
.verdict.no { background: #fef2f2; color: var(--no); }
.why { margin-top: 10px; color: var(--ink); font-size: 14px; }
.src { margin-top: 6px; color: var(--muted); font-size: 12px; }
.err { color: var(--no); font-size: 14px; margin-top: 8px; min-height: 18px; }
.hist { color: var(--muted); font-size: 13px; }
/* leaderboard */
table { width: 100%; border-collapse: collapse; }
th, td { padding: 8px 10px; border-bottom: 1px solid var(--line); text-align: left; }
th.num, td.num { text-align: right; font-variant-numeric: tabular-nums; }
tr.lead td { background: #ecfdf5; font-weight: 700; }
.lb .rank { color: var(--muted); font-variant-numeric: tabular-nums; }
.big { font-size: 20px; }
.rate.weak { color: var(--no); font-weight: 700; }
.cols { display: grid; grid-template-columns: 1fr; gap: 16px; }
@media (min-width: 860px) { .cols { grid-template-columns: 5fr 7fr; } }
.tablewrap { overflow-x: auto; }