:root {
  --ink: #1c2430;
  --muted: #5e6872;
  --paper: #f3efe6;
  --card: #fffdf8;
  --line: #e3d9c8;
  --blue: #1e4e79;
  --blue-soft: #e7f0f7;
  --red: #8d2e2e;
  --red-soft: #f8e8e4;
  --green: #1d6b43;
  --green-soft: #e5f3ea;
  --amber: #8a5a12;
  --shadow: 0 10px 30px rgba(48, 36, 18, 0.06);
  --serif: "Songti SC", "SimSun", "Noto Serif SC", serif;
  --sans: "Segoe UI", "PingFang SC", "Microsoft YaHei", sans-serif;
}

* { box-sizing: border-box; }
html, body { margin: 0; padding: 0; }
body {
  min-height: 100vh;
  color: var(--ink);
  background:
    linear-gradient(180deg, rgba(30, 78, 121, 0.08), transparent 220px),
    var(--paper);
  font-family: var(--sans);
  line-height: 1.6;
}

button, select {
  font: inherit;
  color: inherit;
}
button { cursor: pointer; }
button:disabled { cursor: not-allowed; opacity: 0.45; }
button:focus-visible, select:focus-visible { outline: 2px solid var(--blue); outline-offset: 2px; }

.app { width: min(1040px, calc(100% - 32px)); margin: 0 auto; padding: 28px 0 64px; }

.top { display: flex; justify-content: space-between; gap: 16px; align-items: flex-end; margin-bottom: 22px; }
.eyebrow { margin: 0 0 4px; color: var(--blue); letter-spacing: 0.12em; font-size: 13px; }
h1, h2, h3 { font-family: var(--serif); font-weight: 600; }
h1 { margin: 0; font-size: 40px; line-height: 1.2; }
.lede { margin: 8px 0 0; color: var(--muted); }

.stats, .actions, .history, .parts { margin-top: 18px; }
.stats { display: grid; grid-template-columns: repeat(4, 1fr); gap: 12px; }
.stat, .card, .panel, .question, .summary {
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: 16px;
  box-shadow: var(--shadow);
}
.stat { padding: 16px 18px; }
.stat b { display: block; font-size: 28px; line-height: 1.2; font-family: var(--serif); }
.stat span { color: var(--muted); font-size: 13px; }

.actions { display: flex; flex-wrap: wrap; gap: 10px; }
.btn, .option, .mini, .num {
  border: 1px solid transparent;
  border-radius: 999px;
  padding: 10px 16px;
  background: white;
}
.btn.primary { background: var(--blue); color: white; }
.btn.primary:hover { background: #173e61; }
.btn.ghost { border-color: var(--line); background: transparent; }
.btn.danger { color: var(--red); border-color: #efcfc8; background: white; }
.btn.block { width: 100%; border-radius: 12px; }

.banner {
  display: flex; flex-wrap: wrap; gap: 10px; align-items: center;
  margin-top: 16px; padding: 12px 14px;
  background: #fff6e8; border: 1px solid #efd7ae; border-radius: 14px;
}
.banner p { margin: 0; flex: 1; }

.parts { display: grid; grid-template-columns: 1fr 1fr; gap: 14px; }
.card { padding: 18px; display: flex; flex-direction: column; gap: 10px; }
.card h2 { margin: 0; font-size: 22px; }
.meta { color: var(--muted); font-size: 13px; display: flex; gap: 8px; flex-wrap: wrap; }
.track { height: 8px; background: #efe7da; border-radius: 99px; overflow: hidden; }
.track span { display: block; height: 100%; background: var(--blue); }
.card .row { display: flex; flex-wrap: wrap; gap: 8px; margin-top: auto; }

.history { padding: 0; list-style: none; }
.history li {
  padding: 10px 2px; border-bottom: 1px solid var(--line); color: var(--muted);
}
.section-title { margin: 28px 0 0; font-size: 18px; }

.session-bar, .dock {
  display: flex; align-items: center; justify-content: space-between; gap: 12px;
}
.session-bar { margin-bottom: 14px; }
.session-bar strong { display: block; }
.timer { font-variant-numeric: tabular-nums; font-size: 20px; font-family: var(--serif); }
.timer.urgent { color: var(--red); }

.question, .summary { padding: 22px; }
.tag {
  display: inline-flex; align-items: center;
  padding: 2px 8px; border-radius: 999px;
  background: var(--blue-soft); color: var(--blue); font-size: 12px;
}
.stem { margin: 12px 0 18px; font-size: 20px; line-height: 1.75; font-family: var(--serif); }
.options { display: grid; gap: 10px; }
.options.judge { grid-template-columns: 1fr 1fr; }
.option {
  width: 100%; text-align: left; border-radius: 12px; border-color: var(--line);
  padding: 12px 14px; line-height: 1.55; background: white;
}
.option:hover:not(:disabled) { border-color: #b9cbe0; }
.option.chosen { border-color: var(--blue); background: var(--blue-soft); }
.option.right { border-color: var(--green); background: var(--green-soft); }
.option.wrong { border-color: var(--red); background: var(--red-soft); }
.option b { margin-right: 8px; }

.explain {
  margin-top: 16px; padding: 14px 16px; border-radius: 12px;
  background: #f7f3ea; border: 1px solid var(--line);
}
.explain h3 { margin: 0 0 6px; font-size: 16px; }
.explain.bad h3 { color: var(--red); }
.explain.good h3 { color: var(--green); }
.hint { min-height: 1.2em; color: var(--amber); margin: 8px 0 0; }

.dock {
  position: sticky; bottom: 12px; margin-top: 14px; padding: 10px;
  background: rgba(255, 253, 248, 0.94); border: 1px solid var(--line);
  border-radius: 16px; backdrop-filter: blur(8px);
}

.palette { display: grid; grid-template-columns: repeat(10, 1fr); gap: 6px; margin-top: 16px; }
.num {
  padding: 0; height: 36px; border-radius: 8px; border-color: var(--line); background: white;
}
.num.done { background: var(--blue-soft); border-color: #b7cfe4; }
.num.current { outline: 2px solid var(--blue); }
.num.flagged { box-shadow: inset 0 -3px 0 var(--amber); }
.num.ok { background: var(--green-soft); border-color: #b7dcc6; }
.num.bad { background: var(--red-soft); border-color: #efc7c0; }

.summary h2 { margin-top: 0; }
.breakdown { width: 100%; border-collapse: collapse; margin-top: 8px; }
.breakdown th, .breakdown td { text-align: left; padding: 8px 6px; border-bottom: 1px solid var(--line); }
.foot { margin-top: 28px; color: var(--muted); font-size: 13px; }

dialog {
  width: min(480px, calc(100% - 24px));
  border: 1px solid var(--line); border-radius: 16px; padding: 18px;
  background: var(--card); color: var(--ink);
}
dialog::backdrop { background: rgba(28, 36, 48, 0.35); }
dialog h3 { margin: 0 0 8px; font-family: var(--serif); font-size: 24px; }
.field { display: grid; gap: 6px; margin: 12px 0; }
.field select, .choices { width: 100%; }
.choices { display: grid; gap: 8px; }
.choices label {
  display: flex; gap: 8px; align-items: center;
  padding: 10px 12px; border: 1px solid var(--line); border-radius: 12px;
}
.dialog-actions { display: flex; justify-content: flex-end; gap: 8px; margin-top: 8px; }

@media (max-width: 800px) {
  .app { width: min(100% - 20px, 1040px); padding-top: 18px; }
  h1 { font-size: 32px; }
  .stats, .parts, .options.judge { grid-template-columns: 1fr; }
  .palette { grid-template-columns: repeat(6, 1fr); }
  .stem { font-size: 18px; }
  .top { align-items: flex-start; }
}