:root {
  --bg: #f3f4f6;
  --card: #ffffff;
  --text: #1f2937;
  --muted: #6b7280;
  --primary: #2563eb;
  --primary-dark: #1d4ed8;
  --danger: #dc2626;
  --ok: #16a34a;
  --border: #e5e7eb;
  --radius: 12px;
}

* { box-sizing: border-box; margin: 0; padding: 0; }

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Microsoft YaHei", sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.6;
}

.topbar {
  position: sticky;
  top: 0;
  z-index: 10;
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px 16px;
  padding: 10px 16px;
  background: var(--card);
  border-bottom: 1px solid var(--border);
}

.brand { font-weight: 700; font-size: 17px; }

.nav { display: flex; align-items: center; gap: 4px; flex-wrap: wrap; }
.nav a {
  text-decoration: none;
  color: var(--muted);
  padding: 6px 12px;
  border-radius: 8px;
  font-size: 14px;
}
.nav a:hover { background: var(--bg); color: var(--text); }
.nav a.active { background: var(--primary); color: #fff; }
.nav .user { margin-left: 8px; font-size: 13px; color: var(--muted); }

.container {
  max-width: 820px;
  margin: 16px auto;
  padding: 0 12px;
}

.card {
  background: var(--card);
  border-radius: var(--radius);
  border: 1px solid var(--border);
  padding: 20px;
  margin-bottom: 16px;
}
.card h2 { font-size: 20px; margin-bottom: 12px; }
.card h3 { font-size: 16px; margin-bottom: 12px; }

.muted { color: var(--muted); font-size: 13px; }
.error { color: var(--danger); font-size: 14px; margin-top: 8px; }

.btn, .btn-primary {
  display: inline-block;
  border: 1px solid var(--border);
  background: var(--card);
  color: var(--text);
  padding: 8px 18px;
  border-radius: 8px;
  font-size: 14px;
  cursor: pointer;
  text-decoration: none;
  transition: filter .15s;
}
.btn:hover { filter: brightness(.97); }
.btn:disabled { opacity: .6; cursor: not-allowed; }
.btn-primary {
  background: var(--primary);
  border-color: var(--primary);
  color: #fff;
}
.btn-primary:hover { background: var(--primary-dark); }
.btn-primary:disabled { background: var(--primary); }
.btn-block { width: 100%; margin-top: 16px; padding: 12px; font-size: 16px; }
.btn-danger { color: var(--danger); border-color: var(--danger); }
.btn-sm { padding: 4px 10px; font-size: 13px; }

/* ---------- 表单 ---------- */
label { display: block; font-size: 13px; color: var(--muted); margin: 12px 0 4px; }
input, select, textarea {
  width: 100%;
  padding: 9px 12px;
  border: 1px solid var(--border);
  border-radius: 8px;
  font-size: 14px;
  font-family: inherit;
  background: #fff;
}
input:focus, select:focus, textarea:focus { outline: 2px solid var(--primary); outline-offset: -1px; }
textarea { resize: vertical; }

.auth-card { max-width: 400px; margin: 40px auto; }
.auth-card a { color: var(--primary); text-decoration: none; }
.auth-card .muted { margin-top: 14px; text-align: center; }

/* ---------- 考试 ---------- */
.quiz-meta { display: flex; align-items: center; justify-content: space-between; flex-wrap: wrap; gap: 8px; }

.badge {
  display: inline-block;
  padding: 2px 10px;
  border-radius: 999px;
  font-size: 12px;
  background: #eef2ff;
  color: #4338ca;
}
.badge.type-single { background: #eef2ff; color: #4338ca; }
.badge.type-multi { background: #fdf4ff; color: #a21caf; }
.badge.type-judge { background: #fef3c7; color: #b45309; }
.badge.type-fill { background: #ecfdf5; color: #047857; }
.badge.pass { background: #dcfce7; color: #15803d; }
.badge.fail { background: #fee2e2; color: #b91c1c; }

.question {
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 14px;
  margin-bottom: 14px;
}
.q-head { display: flex; align-items: center; justify-content: space-between; margin-bottom: 6px; }
.q-content { font-size: 15px; margin-bottom: 10px; }
.q-points { font-size: 12px; color: var(--muted); }

.option {
  display: flex;
  align-items: flex-start;
  gap: 10px;
  padding: 10px 12px;
  margin: 6px 0;
  border: 1px solid var(--border);
  border-radius: 8px;
  cursor: pointer;
  font-size: 14px;
  transition: border-color .15s, background .15s;
}
.option:hover { border-color: var(--primary); background: #f8fafc; }
.option:has(input:checked) { border-color: var(--primary); background: #eff6ff; }
.option input { width: auto; margin-top: 3px; }
.option-letter {
  display: inline-flex;
  width: 22px; height: 22px;
  align-items: center; justify-content: center;
  border-radius: 50%;
  background: #e5e7eb;
  font-size: 12px; font-weight: 700;
  flex-shrink: 0;
}

/* ---------- 结果 ---------- */
.result-card { text-align: center; }
.score-box { margin: 10px 0 18px; }
.score-num { font-size: 56px; font-weight: 800; color: var(--primary); line-height: 1.1; }
.score-num small { font-size: 22px; font-weight: 600; color: var(--muted); }
.score-pct { font-size: 15px; margin-top: 4px; }
.result-actions { display: flex; gap: 10px; justify-content: center; flex-wrap: wrap; }
.result-row { border: 1px solid var(--border); border-left: 4px solid var(--muted); border-radius: 8px; padding: 12px; margin-bottom: 10px; }
.result-row.right { border-left-color: var(--ok); }
.result-row.wrong { border-left-color: var(--danger); }
.result-row .ok { color: var(--ok); font-weight: 600; }
.result-row .no { color: var(--danger); font-weight: 600; margin-right: 8px; }
.explain { margin-top: 6px; font-size: 13px; color: #475569; background: #f8fafc; padding: 8px; border-radius: 6px; }

/* ---------- 排行榜 / 表格 ---------- */
.table-wrap { overflow-x: auto; margin-top: 8px; }
.table { width: 100%; border-collapse: collapse; font-size: 14px; }
.table th, .table td { padding: 10px 8px; text-align: left; border-bottom: 1px solid var(--border); white-space: nowrap; }
.table th { color: var(--muted); font-weight: 600; font-size: 13px; }
.table .rank { font-size: 16px; }
.table .name { font-weight: 600; }
.table .score { font-weight: 700; color: var(--primary); }
.table .score small { font-weight: 400; color: var(--muted); }
.table .actions { display: flex; gap: 6px; }

/* ---------- 后台 ---------- */
.tabs { display: flex; gap: 6px; flex-wrap: wrap; margin-bottom: 14px; }
.tabs button {
  padding: 8px 18px;
  border: 1px solid var(--border);
  border-radius: 999px;
  background: var(--card);
  font-size: 14px;
  cursor: pointer;
}
.tabs button.active { background: var(--primary); color: #fff; border-color: var(--primary); }

.stat-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(120px, 1fr));
  gap: 12px;
  margin-bottom: 16px;
}
.stat-card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 16px;
  text-align: center;
}
.stat-card .num { font-size: 28px; font-weight: 800; color: var(--primary); }

.toolbar { display: flex; gap: 8px; flex-wrap: wrap; margin-bottom: 12px; }
.toolbar select, .toolbar input { width: auto; flex: 1; min-width: 120px; }
.q-cell { white-space: normal; min-width: 200px; max-width: 340px; }

.overlay {
  position: fixed;
  inset: 0;
  background: rgba(0,0,0,.45);
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 16px;
  z-index: 100;
}
.modal { width: 100%; max-width: 560px; max-height: 90vh; overflow-y: auto; }
.modal-actions { display: flex; justify-content: flex-end; gap: 10px; margin-top: 16px; }

.footer { text-align: center; color: var(--muted); font-size: 12px; padding: 20px 0 30px; }

@media (min-width: 640px) {
  .container { padding: 0 20px; }
}