:root {
  --bg: #f5f6f8;
  --card: #ffffff;
  --text: #1f2933;
  --muted: #616e7c;
  --primary: #2563eb;
  --border: #d9dee5;
}
@media (prefers-color-scheme: dark) {
  :root {
    --bg: #111827;
    --card: #1f2937;
    --text: #f3f4f6;
    --muted: #9ca3af;
    --primary: #60a5fa;
    --border: #374151;
  }
}
* { box-sizing: border-box; }
body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: system-ui, -apple-system, "Noto Sans TC", sans-serif;
  line-height: 1.6;
}
/* 版面：左側選單 1/3、右側內容 2/3 */
.layout {
  display: grid;
  grid-template-columns: 1fr 2fr;
  gap: 32px;
  max-width: 1200px;
  margin: 0 auto;
  padding: 24px 16px;
  align-items: start;
}
main { min-width: 0; }

.sidebar {
  position: sticky;
  top: 24px;
  max-height: calc(100vh - 48px);
  overflow-y: auto;
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 16px;
}
.brand {
  display: block;
  font-size: 1.2rem;
  font-weight: 800;
  color: var(--text);
  text-decoration: none;
  margin-bottom: 12px;
}
.nav-group {
  margin: 16px 0 6px;
  font-size: 0.8rem;
  font-weight: 700;
  color: var(--muted);
  letter-spacing: 0.05em;
}
.sidebar nav a {
  display: block;
  padding: 8px 10px;
  border-radius: 8px;
  color: var(--text);
  text-decoration: none;
}
.sidebar nav a span { display: block; font-weight: 600; }
.sidebar nav a small { display: block; color: var(--muted); font-size: 0.8rem; }
.sidebar nav a:hover { background: var(--bg); }
.sidebar nav a.active { background: var(--primary); }
.sidebar nav a.active span,
.sidebar nav a.active small { color: #fff; }

/* 手機：選單改成上方可左右滑動的按鈕列 */
@media (max-width: 768px) {
  .layout { grid-template-columns: 1fr; gap: 16px; }
  .sidebar {
    position: static;
    max-height: none;
    padding: 12px;
  }
  .brand { margin-bottom: 8px; }
  .sidebar nav {
    display: flex;
    gap: 6px;
    overflow-x: auto;
    padding-bottom: 4px;
  }
  .nav-group, .sidebar nav a small { display: none; }
  .sidebar nav a {
    flex: 0 0 auto;
    padding: 6px 12px;
    border: 1px solid var(--border);
    border-radius: 999px;
    white-space: nowrap;
  }
  .sidebar nav a span { font-weight: 500; font-size: 0.9rem; }
}
h1 { font-size: 1.6rem; margin: 0 0 4px; }
.sub { color: var(--muted); margin: 0 0 20px; }
.back { display: inline-block; margin-bottom: 12px; color: var(--primary); text-decoration: none; }
.card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 20px;
  margin-bottom: 16px;
}
label { display: block; font-weight: 600; margin: 12px 0 6px; }
input, select {
  width: 100%;
  padding: 10px 12px;
  font-size: 1rem;
  border: 1px solid var(--border);
  border-radius: 8px;
  background: var(--bg);
  color: var(--text);
}
button {
  width: 100%;
  margin-top: 18px;
  padding: 12px;
  font-size: 1rem;
  font-weight: 700;
  color: #fff;
  background: var(--primary);
  border: none;
  border-radius: 8px;
  cursor: pointer;
}
.total { font-size: 2rem; font-weight: 800; color: var(--primary); margin: 4px 0 12px; }
table { width: 100%; border-collapse: collapse; font-size: 0.95rem; }
td { padding: 6px 0; border-bottom: 1px solid var(--border); }
td:last-child { text-align: right; }
.error { color: #dc2626; font-weight: 600; }
.note { font-size: 0.85rem; color: var(--muted); }

/* 常見問題 */
.faq h2 { font-size: 1.2rem; margin: 0 0 8px; }
.faq details { border-bottom: 1px solid var(--border); padding: 10px 0; }
.faq details:last-child { border-bottom: none; }
.faq summary { cursor: pointer; font-weight: 600; }
.faq details p { margin: 8px 0 0; color: var(--muted); }

/* 頁尾瀏覽人次 */
.site-footer { margin-top: 24px; text-align: center; }
#stats iframe { border: none; max-width: 100%; }
.footer-links { font-size: 0.85rem; margin: 0 0 10px; }
.footer-links a { color: var(--muted); margin: 0 8px; }

/* 首頁工具清單 */
.tool {
  display: block;
  text-decoration: none;
  color: var(--text);
}
.tool:hover { border-color: var(--primary); }
.tool h2 { font-size: 1.15rem; margin: 0 0 4px; color: var(--primary); }
.tool p { margin: 0; color: var(--muted); }