:root {
  --primary: #2563eb;
  --primary-dark: #1d4ed8;
  --bg: #f8fafc;
  --card: #ffffff;
  --text: #1e293b;
  --text-soft: #334155;
  --muted: #64748b;
  --border: #e2e8f0;
  --result-bg: #eff6ff;
  --header-grad: linear-gradient(135deg, #1e40af, #3b82f6);
}
[data-theme="dark"] {
  --bg: #0f172a;
  --card: #1e293b;
  --text: #e2e8f0;
  --text-soft: #cbd5e1;
  --muted: #94a3b8;
  --border: #334155;
  --result-bg: #1e3a5f;
  --header-grad: linear-gradient(135deg, #172554, #1e40af);
}
* { margin: 0; padding: 0; box-sizing: border-box; }
body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.6;
  transition: background 0.2s, color 0.2s;
}
header { background: var(--header-grad); color: #fff; padding: 20px 16px 26px; text-align: center; }
.top-bar { display: flex; justify-content: flex-end; gap: 8px; max-width: 860px; margin: 0 auto 10px; }
.top-bar select, .top-bar button {
  background: rgba(255,255,255,0.15); color: #fff; border: 1px solid rgba(255,255,255,0.4);
  border-radius: 8px; padding: 6px 10px; cursor: pointer; font-size: 0.85rem;
}
.top-bar select option { color: #1e293b; }
.logo { display: inline-flex; align-items: center; gap: 10px; margin-bottom: 8px; color: #fff; text-decoration: none; }
.logo svg { width: 38px; height: 38px; }
.logo span { font-size: 1.35rem; font-weight: 700; letter-spacing: 0.5px; }
header h1 { font-size: 1.6rem; margin-bottom: 6px; }
header p { opacity: 0.9; font-size: 0.98rem; }
.site-nav { display: flex; flex-wrap: wrap; gap: 8px; justify-content: center; margin: 16px auto 0; max-width: 860px; }
.site-nav a {
  padding: 7px 14px; border: 1px solid rgba(255,255,255,0.45); border-radius: 18px;
  color: #fff; text-decoration: none; font-size: 0.88rem; transition: all 0.15s;
}
.site-nav a:hover, .site-nav a.active { background: #fff; color: var(--primary-dark); }
.container { max-width: 860px; margin: 0 auto; padding: 16px; }
.converter-card {
  background: var(--card); border: 1px solid var(--border); border-radius: 12px;
  padding: 24px; box-shadow: 0 1px 3px rgba(0,0,0,0.06); margin-top: 16px;
}
.subcat-tabs {
  display: flex; flex-wrap: wrap; gap: 8px; margin-bottom: 20px; padding-bottom: 16px;
  border-bottom: 1px solid var(--border);
}
.subcat-tab {
  padding: 8px 16px; font-size: 0.9rem; font-weight: 600; border-radius: 20px;
  border: 1px solid var(--border); background: var(--bg); color: var(--text);
  cursor: pointer; transition: all 0.2s ease;
}
.subcat-tab:hover { border-color: var(--primary); color: var(--primary); }
.subcat-tab.active {
  background: var(--primary); color: #fff; border-color: var(--primary);
  box-shadow: 0 2px 6px rgba(37,99,235,0.3);
}
.converter-grid { display: grid; grid-template-columns: 1fr auto 1fr; gap: 12px; align-items: end; }
@media (max-width: 768px) {
  header { padding: 12px 14px 14px; }
  .top-bar { margin: 0 auto 6px; gap: 6px; }
  .top-bar select, .top-bar button { padding: 4px 8px; font-size: 0.78rem; }
  .logo { gap: 8px; margin-bottom: 4px; }
  .logo svg { width: 28px; height: 28px; }
  .logo span { font-size: 1.15rem; }
  header h1 { font-size: 1.3rem; margin-bottom: 2px; line-height: 1.25; }
  header p { font-size: 0.82rem; margin-bottom: 8px; line-height: 1.35; opacity: 0.88; }
  .site-nav {
    display: flex; flex-wrap: nowrap; justify-content: flex-start;
    overflow-x: auto; -webkit-overflow-scrolling: touch;
    gap: 6px; margin: 8px -14px 0; padding: 2px 14px 4px;
    scrollbar-width: none;
  }
  .site-nav::-webkit-scrollbar { display: none; }
  .site-nav a { padding: 5px 11px; font-size: 0.78rem; white-space: nowrap; flex-shrink: 0; }
  .container { padding: 10px 12px; }
  .converter-card { margin-top: 4px; padding: 16px 14px; border-radius: 10px; }
  .subcat-tabs {
    gap: 6px; margin-bottom: 14px; padding-bottom: 12px;
    overflow-x: auto; flex-wrap: nowrap; -webkit-overflow-scrolling: touch;
    scrollbar-width: none;
  }
  .subcat-tabs::-webkit-scrollbar { display: none; }
  .subcat-tab { padding: 6px 12px; font-size: 0.8rem; white-space: nowrap; flex-shrink: 0; }
  .converter-grid { grid-template-columns: 1fr; gap: 6px; }
  .swap-btn { width: 38px; height: 38px; font-size: 1.05rem; margin: 2px auto; }
  .field label { margin-bottom: 4px; font-size: 0.8rem; }
  .field input, .field select { padding: 10px; font-size: 0.98rem; margin-bottom: 6px; }
  .result-line { margin-top: 10px; padding: 10px; font-size: 0.95rem; }
  .common-conversions { margin-top: 14px; }
  .common-conversions h3 { margin-bottom: 6px; font-size: 0.88rem; }
  .chips { gap: 6px; }
  .chip { padding: 4px 10px; font-size: 0.76rem; }
}
.field label { display: block; font-size: 0.85rem; color: var(--muted); margin-bottom: 6px; font-weight: 600; }
.field input, .field select {
  width: 100%; padding: 12px; font-size: 1.05rem; border: 1px solid var(--border);
  border-radius: 8px; margin-bottom: 8px; background: var(--card); color: var(--text);
}
.field input:focus, .field select:focus { outline: 2px solid var(--primary); border-color: transparent; }
.swap-btn {
  background: var(--primary); color: #fff; border: none; border-radius: 50%;
  width: 44px; height: 44px; font-size: 1.2rem; cursor: pointer; margin-bottom: 8px;
  justify-self: center; transition: background 0.15s;
}
.swap-btn:hover { background: var(--primary-dark); }
.result-line {
  margin-top: 16px; padding: 14px; background: var(--result-bg); border-radius: 8px;
  font-size: 1.05rem; text-align: center; font-weight: 600; color: var(--primary);
  word-wrap: break-word;
}
.common-conversions { margin-top: 24px; }
.common-conversions h3 { font-size: 1rem; margin-bottom: 10px; color: var(--muted); }
.chips { display: flex; flex-wrap: wrap; gap: 8px; }
.chip {
  font-size: 0.82rem; padding: 6px 12px; background: var(--bg); color: var(--text);
  border: 1px solid var(--border); border-radius: 16px; cursor: pointer;
}
.chip:hover { border-color: var(--primary); color: var(--primary); }
section.content { margin: 32px 0; }
section.content h2 { font-size: 1.3rem; margin: 24px 0 10px; }
section.content h3 { font-size: 1.05rem; margin: 16px 0 6px; }
section.content p, section.content li { color: var(--text-soft); margin-bottom: 10px; }
section.content ul { padding-left: 22px; margin-bottom: 10px; }
section.content a { color: var(--primary); }
.table-wrapper { width: 100%; overflow-x: auto; -webkit-overflow-scrolling: touch; margin: 10px 0 18px; border-radius: 8px; border: 1px solid var(--border); }
.conv-table { width: 100%; border-collapse: collapse; min-width: 480px; margin: 0; }
.conv-table th, .conv-table td { border: 1px solid var(--border); padding: 10px 14px; text-align: left; font-size: 0.92rem; color: var(--text-soft); }
.conv-table th { background: var(--bg); color: var(--text); font-weight: 600; }
.category-links { display: grid; grid-template-columns: repeat(auto-fill, minmax(230px, 1fr)); gap: 12px; margin: 14px 0; }
.category-links a {
  display: block; background: var(--card); border: 1px solid var(--border); border-radius: 10px;
  padding: 14px 16px; text-decoration: none; color: var(--text); transition: border-color 0.15s;
}
.category-links a:hover { border-color: var(--primary); }
.category-links a strong { color: var(--primary); display: block; margin-bottom: 4px; }
.category-links a span { font-size: 0.85rem; color: var(--muted); }
.faq-item { background: var(--card); border: 1px solid var(--border); border-radius: 8px; padding: 14px 16px; margin-bottom: 10px; }
.faq-item h3 { margin: 0 0 6px; font-size: 1rem; }
.faq-item p { margin: 0; }
footer { text-align: center; padding: 24px; color: var(--muted); font-size: 0.85rem; border-top: 1px solid var(--border); margin-top: 32px; }
footer a { color: var(--muted); margin: 0 5px; }