:root {
  --bg0: #07111f;
  --bg1: #0d1b2e;
  --bg2: #13263d;
  --card: #15253c;
  --line: #2a4365;
  --gold: #f5c542;
  --gold-d: #c49212;
  --ok: #2ecc71;
  --bad: #ff5c5c;
  --info: #4da3ff;
  --text: #e8eef7;
  --muted: #93a4bb;
  --shadow: 0 12px 40px rgba(0, 0, 0, 0.35);
}

* { box-sizing: border-box; margin: 0; padding: 0; }
html, body { height: 100%; }
body {
  font-family: "Microsoft YaHei", "PingFang SC", sans-serif;
  background:
    radial-gradient(1200px 500px at 10% -10%, rgba(245, 197, 66, 0.12), transparent 50%),
    radial-gradient(900px 400px at 100% 0%, rgba(77, 163, 255, 0.12), transparent 45%),
    var(--bg0);
  color: var(--text);
  min-height: 100vh;
}

.app { max-width: 1100px; margin: 0 auto; padding: 20px 16px 48px; }

.topbar {
  display: flex; align-items: center; justify-content: space-between;
  gap: 12px; margin-bottom: 20px; flex-wrap: wrap;
}
.brand { display: flex; align-items: center; gap: 12px; }
.logo {
  width: 46px; height: 46px; border-radius: 12px;
  background: linear-gradient(145deg, var(--gold), #ffe08a);
  color: #1a1304; font-weight: 800; display: grid; place-items: center;
  box-shadow: 0 0 24px rgba(245, 197, 66, 0.35);
  border: none; cursor: pointer; font-size: inherit; padding: 0; line-height: 1;
}
.logo:hover { filter: brightness(1.05); }
.logo:focus-visible {
  outline: 2px solid var(--gold);
  outline-offset: 2px;
}
.brand h1 { font-size: 20px; letter-spacing: 0.5px; }
.brand p { color: var(--muted); font-size: 12px; margin-top: 2px; }
.meta-pill {
  font-size: 12px; color: var(--muted); border: 1px solid var(--line);
  padding: 6px 10px; border-radius: 999px; background: rgba(255,255,255,0.03);
}

.view { display: none; }
.view.active { display: block; }

.hero {
  background: linear-gradient(180deg, rgba(245,197,66,0.08), transparent 40%), var(--card);
  border: 1px solid var(--line); border-radius: 18px; padding: 22px;
  box-shadow: var(--shadow); margin-bottom: 16px;
}
.hero h2 { font-size: 22px; margin-bottom: 8px; }
.hero .rules { color: var(--muted); line-height: 1.7; font-size: 14px; }

.stats {
  display: grid; grid-template-columns: repeat(4, 1fr); gap: 12px; margin: 16px 0;
}
.stat {
  background: var(--bg2); border: 1px solid var(--line); border-radius: 14px; padding: 14px;
}
.stat b { display: block; font-size: 22px; color: var(--gold); }
.stat span { color: var(--muted); font-size: 12px; }

.grid-cards {
  display: grid; grid-template-columns: repeat(2, 1fr); gap: 12px;
}
.action {
  text-align: left; width: 100%; cursor: pointer; color: inherit;
  background: var(--card); border: 1px solid var(--line); border-radius: 16px;
  padding: 18px; box-shadow: var(--shadow); transition: 0.15s transform, 0.15s border-color;
}
.action:hover { transform: translateY(-2px); border-color: var(--gold); }
.action h3 { margin-bottom: 6px; }
.action p { color: var(--muted); font-size: 13px; line-height: 1.6; }
.tag {
  display: inline-block; font-size: 11px; padding: 2px 8px; border-radius: 999px;
  background: rgba(245,197,66,0.15); color: var(--gold); margin-bottom: 8px;
}

.toolbar {
  display: flex; gap: 8px; flex-wrap: wrap; margin-bottom: 12px; align-items: center;
}
select, button, .btn {
  font-family: inherit; font-size: 14px;
}
select {
  background: var(--bg2); color: var(--text); border: 1px solid var(--line);
  border-radius: 10px; padding: 8px 10px;
}
.btn {
  border: 0; border-radius: 10px; padding: 9px 14px; cursor: pointer; font-weight: 600;
  background: var(--gold); color: #1a1304;
}
.btn.ghost {
  background: transparent; color: var(--text); border: 1px solid var(--line);
}
.btn.danger { background: var(--bad); color: #fff; }
.btn.info { background: var(--info); color: #061425; }

.progress-wrap { margin: 8px 0 14px; }
.progress-text { display: flex; justify-content: space-between; color: var(--muted); font-size: 12px; margin-bottom: 6px; }
.bar { height: 8px; background: #0b1726; border-radius: 99px; overflow: hidden; }
.bar > i { display: block; height: 100%; width: 0; background: linear-gradient(90deg, var(--gold), #ffe08a); }

.card {
  background: var(--card); border: 1px solid var(--line); border-radius: 16px;
  padding: 20px; box-shadow: var(--shadow);
}
.q-head { display: flex; justify-content: space-between; gap: 8px; margin-bottom: 10px; color: var(--muted); font-size: 13px; }
.stem { font-size: 18px; line-height: 1.7; margin-bottom: 16px; }
.stem .q-img {
  display: block;
  max-width: min(100%, 560px);
  width: auto;
  height: auto;
  margin: 12px 0 4px;
  border-radius: 8px;
  background: #f3f4f6;
  border: 1px solid #e5e7eb;
}
.options { display: grid; gap: 8px; }
.opt {
  width: 100%; text-align: left; background: var(--bg2); color: var(--text);
  border: 1px solid var(--line); border-radius: 12px; padding: 12px 14px; cursor: pointer;
}
.opt:hover { border-color: var(--gold); }
.opt.picked { border-color: var(--info); box-shadow: inset 0 0 0 1px var(--info); }
.opt.right { border-color: var(--ok); background: rgba(46,204,113,0.12); }
.opt.wrong { border-color: var(--bad); background: rgba(255,92,92,0.12); }
.opt:disabled { cursor: default; }

.explain {
  margin-top: 14px; padding: 12px 14px; border-radius: 12px;
  background: rgba(77,163,255,0.08); border: 1px solid rgba(77,163,255,0.25);
  line-height: 1.7; font-size: 14px; display: none;
}
.explain.show { display: block; }
.explain.ok { background: rgba(46,204,113,0.08); border-color: rgba(46,204,113,0.3); }
.explain.bad { background: rgba(255,92,92,0.08); border-color: rgba(255,92,92,0.3); }

.nav-btns { display: flex; gap: 8px; margin-top: 16px; flex-wrap: wrap; }

.timer {
  font-variant-numeric: tabular-nums; font-weight: 700; color: var(--gold);
}
.timer.warn { color: var(--bad); }

.result-score { font-size: 56px; font-weight: 800; text-align: center; }
.result-score.pass { color: var(--ok); }
.result-score.fail { color: var(--bad); }
.result-sub { text-align: center; color: var(--muted); margin: 6px 0 18px; }

.wrong-item {
  border: 1px solid var(--line); border-radius: 12px; padding: 14px; margin-bottom: 10px; background: var(--bg2);
}
.wrong-item .mini { color: var(--muted); font-size: 12px; margin-bottom: 6px; }
.empty { color: var(--muted); text-align: center; padding: 40px 10px; }

.history { margin-top: 16px; }
.history table { width: 100%; border-collapse: collapse; font-size: 13px; }
.history th, .history td { border-bottom: 1px solid var(--line); padding: 8px 6px; text-align: left; }
.history th { color: var(--muted); font-weight: 600; }

footer { margin-top: 22px; color: #6f829a; font-size: 12px; line-height: 1.7; }

.auth-bar { display: flex; align-items: center; gap: 8px; flex-wrap: wrap; justify-content: flex-end; }

.modal {
  position: fixed; inset: 0; z-index: 1000;
  background: rgba(4, 10, 20, 0.72);
  display: grid; place-items: center; padding: 16px;
}
.modal[hidden] { display: none !important; }
.modal-card {
  width: min(420px, 100%);
  background: var(--card); border: 1px solid var(--line); border-radius: 16px;
  padding: 20px; box-shadow: var(--shadow);
}
.modal-card h3 { margin-bottom: 8px; }
.modal-card label {
  display: block; margin-top: 10px; color: var(--muted); font-size: 13px;
}
.modal-card input {
  display: block; width: 100%; margin-top: 6px;
  background: var(--bg2); color: var(--text); border: 1px solid var(--line);
  border-radius: 10px; padding: 10px 12px; font-family: inherit; font-size: 14px;
}
.login-err { color: var(--bad); font-size: 13px; margin-top: 8px; }

@media (max-width: 800px) {
  .stats, .grid-cards { grid-template-columns: 1fr 1fr; }
  .stem { font-size: 16px; }
}
@media (max-width: 520px) {
  .stats { grid-template-columns: 1fr 1fr; }
  .grid-cards { grid-template-columns: 1fr; }
}