/* ============================================================
 * UnitsConverter.top — 全站样式
 * 主题：靛蓝 + 琥珀点缀，卡片式布局，移动端优先响应式
 * ============================================================ */

:root {
  --primary: #4f46e5;        /* indigo-600 */
  --primary-dark: #4338ca;
  --primary-light: #eef2ff;
  --accent: #f59e0b;         /* amber-500 */
  --ink: #1e293b;
  --ink-soft: #475569;
  --ink-faint: #94a3b8;
  --bg: #f6f7fb;
  --card: #ffffff;
  --line: #e2e8f0;
  --radius: 14px;
  --shadow: 0 1px 3px rgba(15, 23, 42, .06), 0 8px 24px rgba(15, 23, 42, .06);
  --ok: #059669;
}

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

html { -webkit-text-size-adjust: 100%; }

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, "Noto Sans", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  background: var(--bg);
  color: var(--ink);
  line-height: 1.6;
  font-size: 16px;
}

.wrap { max-width: 1080px; margin: 0 auto; padding: 0 20px; }

/* ---------- 页头 ---------- */
.site-header {
  background: var(--card);
  border-bottom: 1px solid var(--line);
  position: sticky; top: 0; z-index: 50;
}
.header-inner {
  display: flex; align-items: center; justify-content: space-between;
  height: 60px; gap: 12px;
}
.brand {
  display: flex; align-items: center; gap: 9px;
  font-size: 20px; font-weight: 800; color: var(--ink); text-decoration: none;
  letter-spacing: -.02em; white-space: nowrap;
}
.brand em { color: var(--primary); font-style: normal; }
.brand-icon { flex: none; }
.site-nav { display: flex; align-items: center; gap: 4px; }
.site-nav a {
  color: var(--ink-soft); text-decoration: none; font-size: 14.5px; font-weight: 500;
  padding: 7px 11px; border-radius: 8px;
}
.site-nav a:hover { color: var(--primary); background: var(--primary-light); }
.lang-select {
  margin-left: 6px; padding: 7px 9px; border: 1px solid var(--line); border-radius: 8px;
  font-size: 14px; color: var(--ink); background: var(--card); cursor: pointer;
}
.lang-select:focus { outline: 2px solid var(--primary); outline-offset: 1px; }

/* ---------- 首屏 ---------- */
.hero { text-align: center; padding: 44px 0 26px; }
.hero h1 {
  font-size: clamp(26px, 4.6vw, 40px); font-weight: 800; letter-spacing: -.03em;
  background: linear-gradient(120deg, var(--primary) 10%, #7c3aed 55%, var(--accent) 100%);
  -webkit-background-clip: text; background-clip: text; -webkit-text-fill-color: transparent;
}
.hero-sub {
  margin: 12px auto 0; max-width: 720px;
  color: var(--ink-soft); font-size: clamp(14.5px, 2vw, 17px);
}

/* ---------- 类别选项卡 ---------- */
.cat-tabs {
  display: flex; flex-wrap: wrap; gap: 8px; justify-content: center;
  margin: 26px 0 18px; role: tablist;
}
.cat-tab {
  display: inline-flex; align-items: center; gap: 7px;
  padding: 9px 15px; border: 1px solid var(--line); border-radius: 999px;
  background: var(--card); color: var(--ink-soft);
  font-size: 14.5px; font-weight: 600; cursor: pointer;
  transition: all .15s ease;
}
.cat-tab:hover { border-color: var(--primary); color: var(--primary); }
.cat-tab.active {
  background: var(--primary); border-color: var(--primary); color: #fff;
  box-shadow: 0 4px 14px rgba(79, 70, 229, .35);
}
.cat-ico { display: inline-flex; width: 18px; height: 18px; }
.cat-ico svg { width: 18px; height: 18px; }
.cat-desc { text-align: center; color: var(--ink-faint); font-size: 14px; margin-bottom: 18px; min-height: 1.4em; }

/* ---------- 转换器卡片 ---------- */
.converter-card {
  background: var(--card); border-radius: var(--radius); box-shadow: var(--shadow);
  border: 1px solid var(--line); padding: 26px;
}
.conv-grid {
  display: grid; grid-template-columns: 1fr auto 1fr; gap: 16px; align-items: end;
}
.conv-panel label {
  display: block; font-size: 13px; font-weight: 700; text-transform: uppercase;
  letter-spacing: .06em; color: var(--ink-faint); margin-bottom: 8px;
}
.conv-input {
  width: 100%; padding: 14px 16px; font-size: 22px; font-weight: 600;
  border: 2px solid var(--line); border-radius: 12px; color: var(--ink);
  background: #fbfcfe; transition: border-color .15s ease;
}
.conv-input:focus { outline: none; border-color: var(--primary); background: #fff; }
.conv-input[readonly] { background: var(--primary-light); border-color: #c7d2fe; color: var(--primary-dark); }
.unit-select {
  width: 100%; margin-top: 10px; padding: 11px 12px; font-size: 15px;
  border: 1px solid var(--line); border-radius: 10px; background: var(--card);
  color: var(--ink); cursor: pointer;
}
.unit-select:focus { outline: 2px solid var(--primary); outline-offset: 1px; }

.swap-btn {
  width: 46px; height: 46px; margin-bottom: 38px;
  border: none; border-radius: 50%; background: var(--primary); color: #fff;
  cursor: pointer; display: inline-flex; align-items: center; justify-content: center;
  transition: transform .2s ease, background .15s ease;
  box-shadow: 0 4px 12px rgba(79, 70, 229, .4);
}
.swap-btn:hover { background: var(--primary-dark); transform: rotate(180deg); }
.swap-btn svg { width: 22px; height: 22px; }

/* 公式条 */
.formula-bar {
  margin-top: 18px; padding: 12px 16px; border-radius: 10px;
  background: linear-gradient(90deg, var(--primary-light), #fdf6e9);
  color: var(--primary-dark); font-size: 15px; font-weight: 600;
  font-variant-numeric: tabular-nums; text-align: center;
}

/* 操作行 */
.conv-actions {
  display: flex; flex-wrap: wrap; align-items: center; gap: 10px; margin-top: 18px;
}
.btn {
  padding: 11px 20px; border-radius: 10px; font-size: 15px; font-weight: 600;
  border: 1px solid var(--line); background: var(--card); color: var(--ink-soft);
  cursor: pointer; transition: all .15s ease;
}
.btn:hover { border-color: var(--primary); color: var(--primary); }
.btn-primary {
  background: var(--primary); border-color: var(--primary); color: #fff;
}
.btn-primary:hover { background: var(--primary-dark); color: #fff; }
.precision-wrap { margin-left: auto; display: flex; align-items: center; gap: 8px; }
.precision-wrap label { font-size: 13.5px; color: var(--ink-faint); font-weight: 600; }
.precision-wrap select {
  padding: 9px 10px; border: 1px solid var(--line); border-radius: 8px;
  font-size: 14px; background: var(--card); cursor: pointer;
}

/* 快捷 chips */
.chips-row { display: flex; flex-wrap: wrap; gap: 8px; margin-top: 16px; }
.chips-label { width: 100%; font-size: 13px; font-weight: 700; color: var(--ink-faint); text-transform: uppercase; letter-spacing: .06em; }
.chip {
  padding: 7px 14px; border-radius: 999px; border: 1px dashed #c7d2fe;
  background: #fff; color: var(--primary-dark); font-size: 14px; font-weight: 600;
  cursor: pointer; transition: all .14s ease; font-variant-numeric: tabular-nums;
}
.chip:hover { background: var(--primary); border-color: var(--primary); color: #fff; border-style: solid; }

/* 历史记录 */
.history-wrap { margin-top: 16px; }
.history-list { display: flex; flex-wrap: wrap; gap: 8px; margin-top: 6px; }
.hist-item {
  padding: 6px 12px; border-radius: 8px; border: 1px solid var(--line);
  background: #f8fafc; color: var(--ink-soft); font-size: 13.5px; cursor: pointer;
  font-variant-numeric: tabular-nums;
}
.hist-item:hover { border-color: var(--accent); color: var(--ink); background: #fffbeb; }

/* ---------- 换算表 ---------- */
.table-card {
  margin-top: 26px; background: var(--card); border-radius: var(--radius);
  box-shadow: var(--shadow); border: 1px solid var(--line); padding: 22px 26px;
}
.table-card h2 { font-size: 19px; font-weight: 750; letter-spacing: -.01em; }
.table-caption { color: var(--primary-dark); font-weight: 700; margin: 4px 0 12px; font-variant-numeric: tabular-nums; }
.conv-table { width: 100%; border-collapse: collapse; font-size: 15px; }
.conv-table th {
  text-align: left; padding: 9px 10px; font-size: 12.5px; text-transform: uppercase;
  letter-spacing: .06em; color: var(--ink-faint); border-bottom: 2px solid var(--line);
}
.conv-table td { padding: 9px 10px; border-bottom: 1px solid #eef2f7; }
.conv-table tbody tr { cursor: pointer; transition: background .12s ease; }
.conv-table tbody tr:hover { background: var(--primary-light); }
.conv-table tr.hl { background: #fdf6e9; }
.conv-table tr.hl:hover { background: #fdf0d5; }
.c-val { font-weight: 650; font-variant-numeric: tabular-nums; }
.c-sym { color: var(--ink-faint); }
.table-empty { text-align: center; color: var(--ink-faint); padding: 22px 10px !important; cursor: default; }

/* ---------- 内容区 ---------- */
.content-section { margin-top: 46px; }
.content-section h2 { font-size: 24px; font-weight: 750; letter-spacing: -.02em; margin-bottom: 14px; }
.content-section h3 { font-size: 17px; font-weight: 700; margin-bottom: 6px; }
.content-section p { color: var(--ink-soft); margin-bottom: 12px; max-width: 76ch; }
.howto-list { padding-left: 22px; color: var(--ink-soft); }
.howto-list li { margin-bottom: 8px; }
.feature-grid {
  display: grid; grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: 14px; margin-top: 16px;
}
.feature-item {
  background: var(--card); border: 1px solid var(--line); border-radius: 12px; padding: 18px;
}
.feature-item p { font-size: 14.5px; margin: 0; }

/* FAQ */
.faq-list { display: grid; gap: 10px; margin-top: 14px; }
.faq-item {
  background: var(--card); border: 1px solid var(--line); border-radius: 12px;
  padding: 4px 18px;
}
.faq-item summary {
  cursor: pointer; font-weight: 650; font-size: 15.5px; padding: 13px 0;
  list-style: none; position: relative; padding-right: 28px;
}
.faq-item summary::after {
  content: "+"; position: absolute; right: 2px; top: 50%; transform: translateY(-50%);
  font-size: 20px; color: var(--primary); font-weight: 700;
}
.faq-item[open] summary::after { content: "–"; }
.faq-item summary::-webkit-details-marker { display: none; }
.faq-item p { padding: 0 0 14px; color: var(--ink-soft); font-size: 15px; }

/* ---------- 页脚 ---------- */
.site-footer {
  margin-top: 60px; border-top: 1px solid var(--line);
  background: var(--card); padding: 28px 0 34px;
}
.footer-inner { text-align: center; color: var(--ink-soft); font-size: 14px; }
.footer-nav { display: flex; flex-wrap: wrap; gap: 6px 18px; justify-content: center; margin: 12px 0; }
.footer-nav a { color: var(--ink-soft); text-decoration: none; font-weight: 550; }
.footer-nav a:hover { color: var(--primary); }
.disclaimer { color: var(--ink-faint); font-size: 13px; margin-top: 10px; }

/* ---------- 合规页（privacy/about/contact） ---------- */
.legal { max-width: 780px; padding-top: 36px; padding-bottom: 20px; }
.legal h1 { font-size: 30px; font-weight: 800; letter-spacing: -.02em; margin-bottom: 16px; }
.legal h2 { font-size: 20px; font-weight: 750; margin: 26px 0 10px; }
.legal h3 { font-size: 16.5px; font-weight: 700; margin: 18px 0 6px; }
.legal p, .legal li { color: var(--ink-soft); margin-bottom: 10px; }
.legal ul, .legal ol { padding-left: 22px; margin-bottom: 12px; }
.legal a { color: var(--primary); }
.callout {
  background: var(--primary-light); border-left: 4px solid var(--primary);
  padding: 13px 16px; border-radius: 0 10px 10px 0; font-weight: 550;
}

/* ---------- 移动端 ---------- */
@media (max-width: 720px) {
  .header-inner { height: auto; padding: 10px 0; flex-wrap: wrap; }
  .brand { font-size: 18px; }
  .site-nav { flex-wrap: wrap; }
  .hero { padding: 30px 0 18px; }
  .converter-card { padding: 18px 14px; }
  .conv-grid { grid-template-columns: 1fr; gap: 10px; }
  .swap-btn { margin: 2px auto; transform: rotate(90deg); }
  .swap-btn:hover { transform: rotate(270deg); }
  .conv-input { font-size: 19px; padding: 12px 14px; }
  .precision-wrap { margin-left: 0; width: 100%; }
  .content-section { margin-top: 36px; }
  .conv-table .c-name { max-width: 110px; }
}