/* frontend.车载雷达.公司 — 原创浅色高端科技风骨架（frt- 前缀，零复用） */
:root {
  --ink: #0A1428;          /* 深墨蓝黑 */
  --rf-purple: #7C5CFF;    /* 射频紫 */
  --h-cyan: #18E0C8;       /* 氢光青 */
  --warm-gold: #E8B04B;    /* 暖金 */
  --bg: #F5F7FA;           /* 浅色高端底 */
  --panel: #FFFFFF;
  --text: #1C2533;
  --muted: #5B6678;
  --line: #D7DEE8;
  --line-strong: #cbd5e1;
  --h2-inset: 16px;        /* 面包屑与 H2 左缘对齐 */
  --maxw: 1180px;
  --nav-h: 64px;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  font-family: -apple-system, "Segoe UI", "PingFang SC", "Microsoft YaHei", sans-serif;
  color: var(--text);
  background: var(--bg);
  line-height: 1.75;
  font-size: 16px;
}
a { color: var(--rf-purple); text-decoration: none; }
a:hover { color: var(--h-cyan); }
img { max-width: 100%; }

/* ===== 顶部固定导航 ===== */
.frt-nav {
  position: fixed; top: 0; left: 0; right: 0; height: var(--nav-h);
  background: rgba(10,20,40,0.92);
  backdrop-filter: blur(8px);
  display: flex; align-items: center;
  padding: 0 24px; z-index: 1000;
  border-bottom: 1px solid rgba(124,92,255,0.35);
}
.frt-nav-inner {
  max-width: var(--maxw); margin: 0 auto; width: 100%;
  display: flex; align-items: center; gap: 10px;
}
.frt-brand { color: #fff; font-weight: 700; font-size: 17px; letter-spacing: .5px; white-space: nowrap; }
.frt-brand b { color: var(--h-cyan); }
.frt-nav-spacer { flex: 1; }
.frt-nav-link { color: #cdd6e6; padding: 8px 12px; border-radius: 8px; font-size: 14px; }
.frt-nav-link:hover { color: #fff; background: rgba(124,92,255,0.25); }
.frt-nav-toggle { display: none; background: none; border: 0; color: #fff; font-size: 22px; cursor: pointer; }
.frt-nav-menu { display: flex; align-items: center; gap: 2px; margin-left: auto; }

/* 顶部导航下拉（桌面 hover 展开） */
.frt-nav-item { position: relative; }
.frt-nav-sub {
  position: absolute; top: 100%; left: 0;
  background: #0d1830; border: 1px solid rgba(124,92,255,0.4);
  border-radius: 10px; padding: 8px; min-width: 180px;
  display: none; flex-direction: column; gap: 2px;
}
.frt-nav-item:hover .frt-nav-sub, .frt-nav-item:focus-within .frt-nav-sub { display: flex; }
.frt-nav-sub a { color: #cdd6e6; padding: 7px 10px; border-radius: 6px; font-size: 13px; }
.frt-nav-sub a:hover { background: rgba(124,92,255,0.2); color: #fff; }

/* ===== 容器 ===== */
.frt-container { max-width: var(--maxw); margin: 0 auto; padding: 0 24px; }
.frt-main { padding-top: calc(var(--nav-h) + 24px); }

/* ===== 面包屑 ===== */
.frt-crumb {
  font-size: 13px; color: var(--muted);
  padding-left: var(--h2-inset); margin: 18px 0 8px;
}
.frt-crumb a { color: var(--muted); }
.frt-crumb a:hover { color: var(--rf-purple); }
.frt-crumb span.sep { margin: 0 8px; color: var(--line-strong); }

/* ===== 详情页布局（内容 + TOC） ===== */
.frt-article-layout, .frt-product-layout {
  --h2-inset: 16px;
  display: grid; grid-template-columns: minmax(0, 1fr) 240px;
  gap: 40px; align-items: start;
  max-width: var(--maxw); margin: 0 auto; padding: 0 24px 60px;
}
.frt-content-main { min-width: 0; max-width: 760px; }
.frt-content-main h1 { font-size: 30px; line-height: 1.3; color: var(--ink); margin: 6px 0 18px; }
.frt-content-main h2 {
  font-size: 22px; color: var(--ink); margin: 36px 0 14px;
  padding-left: var(--h2-inset); border-left: 4px solid var(--rf-purple);
}
.frt-content-main h3 { font-size: 18px; color: var(--ink); margin: 24px 0 10px; padding-left: var(--h2-inset); }
.frt-content-main p { margin: 0 0 16px; }
.frt-content-main ul, .frt-content-main ol { padding-left: 28px; margin: 0 0 16px; }
.frt-content-main li { margin: 6px 0; }
.frt-summary-block {
  background: linear-gradient(135deg, rgba(124,92,255,0.08), rgba(24,224,200,0.08));
  border: 1px solid var(--line); border-left: 4px solid var(--h-cyan);
  border-radius: 12px; padding: 18px 20px; margin: 0 0 22px;
}
.frt-keywords { font-size: 13px; color: var(--muted); margin: 0 0 18px; }
.frt-keywords b { color: var(--rf-purple); }
.frt-update-time { font-size: 13px; color: var(--muted); margin: 0 0 22px; }
.frt-conclusion { background: #fff; border: 1px solid var(--line); border-radius: 12px; padding: 16px 20px; margin: 24px 0; }
.frt-conclusion h2 { border: 0; padding-left: 0; }
.frt-case { background: #fff8ec; border: 1px solid #f3dcae; border-radius: 12px; padding: 16px 20px; margin: 24px 0; }
.frt-case h3 { color: #9a6b14; }

/* ===== 表格（覆盖正文全部 table，含 Markdown 裸 table） ===== */
.frt-content-main table, .frt-page-main table, table.frt-spec {
  border-collapse: collapse; width: 100%; margin: 18px 0;
  font-size: 14px; border: 1px solid var(--line-strong);
}
.frt-content-main table th, .frt-page-main table th, table.frt-spec th {
  background: var(--ink); color: #fff; text-align: left; padding: 10px 12px; font-weight: 600;
}
.frt-content-main table td, .frt-page-main table td, table.frt-spec td {
  border: 1px solid var(--line-strong); padding: 9px 12px;
}
.frt-content-main table tr:nth-child(even) td,
.frt-page-main table tr:nth-child(even) td,
table.frt-spec tr:nth-child(even) td { background: #eef2f8; }

/* ===== TOC 目录（原生 details 折叠，sticky） ===== */
.frt-toc-panel {
  position: sticky; top: calc(var(--nav-h) + 16px);
  max-height: calc(100vh - var(--nav-h) - 32px); overflow-y: auto;
  background: var(--panel); border: 1px solid var(--line); border-radius: 12px; padding: 14px 16px;
}
.frt-toc-panel summary { cursor: pointer; font-weight: 600; color: var(--ink); list-style: none; }
.frt-toc-panel summary::after { content: "▾"; float: right; color: var(--rf-purple); }
.frt-toc-panel[open] summary::after { content: "▴"; }
.frt-toc-panel ol { margin: 10px 0 0; padding-left: 20px; }
.frt-toc-panel li { margin: 6px 0; font-size: 13px; }
.frt-toc-panel a { color: var(--muted); }
.frt-toc-panel a:hover { color: var(--rf-purple); }

/* ===== 列表 / 分类页（侧栏在前 → 240px 居左，内容 1fr） ===== */
.frt-list-layout {
  --h2-inset: 16px;
  display: grid; grid-template-columns: 240px minmax(0, 1fr);
  gap: 32px; align-items: start;
  max-width: var(--maxw); margin: 0 auto; padding: 0 24px 60px;
}
.frt-cat-side { position: sticky; top: calc(var(--nav-h) + 16px); }
.frt-cat-panel { background: var(--panel); border: 1px solid var(--line); border-radius: 12px; padding: 12px 14px; }
.frt-cat-panel summary { cursor: pointer; font-weight: 600; color: var(--ink); list-style: none; }
.frt-cat-panel summary::after { content: "▾"; float: right; color: var(--rf-purple); }
.frt-cat-panel[open] summary::after { content: "▴"; }
ul.frt-category-list { list-style: none; margin: 10px 0 0; padding: 0; }
ul.frt-category-list li { margin: 2px 0; }
ul.frt-category-list a { display: block; padding: 8px 10px; border-radius: 8px; color: var(--text); font-size: 14px; }
ul.frt-category-list a:hover, ul.frt-category-list a.active { background: rgba(124,92,255,0.12); color: var(--rf-purple); font-weight: 600; }
.frt-cat-content h1 { font-size: 28px; color: var(--ink); margin: 4px 0 10px; }
.frt-cat-desc { color: var(--muted); margin: 0 0 22px; }
.frt-card-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(280px, 1fr)); gap: 18px; }
.frt-card {
  background: var(--panel); border: 1px solid var(--line); border-radius: 14px;
  padding: 18px 20px; transition: transform .15s, box-shadow .15s;
}
.frt-card:hover { transform: translateY(-3px); box-shadow: 0 10px 30px rgba(124,92,255,0.15); }
.frt-card h3 { margin: 0 0 8px; font-size: 17px; }
.frt-card h3 a { color: var(--ink); }
.frt-card p { margin: 0 0 10px; font-size: 14px; color: var(--muted); }
.frt-card .frt-cat-tag { display: inline-block; font-size: 12px; color: var(--rf-purple); background: rgba(124,92,255,0.1); border-radius: 6px; padding: 2px 8px; }

/* ===== 页面（about/contact 等） ===== */
.frt-page-main { --h2-inset: 48px; max-width: 880px; margin: 0 auto; padding: 0 24px 60px; }
.frt-page-main h1 { font-size: 30px; color: var(--ink); margin: 6px 0 18px; }
.frt-page-main h2 { font-size: 22px; color: var(--ink); margin: 32px 0 12px; padding-left: 48px; border-left: 4px solid var(--warm-gold); }
.frt-page-main p { margin: 0 0 16px; }
.frt-page-main ul { padding-left: 28px; }

/* ===== FAQ（裸 details，faq_dom: bare_details） ===== */
.frt-content-main details { background: var(--panel); border: 1px solid var(--line); border-radius: 10px; padding: 0 16px; margin: 12px 0; }
.frt-content-main details summary { cursor: pointer; padding: 14px 0; font-weight: 600; color: var(--ink); list-style: none; }
.frt-content-main details summary::after { content: "+"; float: right; color: var(--rf-purple); font-size: 20px; }
.frt-content-main details[open] summary::after { content: "−"; }
.frt-content-main details > div { padding: 0 0 14px; color: var(--text); }

/* ===== 悬浮工具胶囊 ===== */
.frt-float { position: fixed; right: 18px; top: 50%; transform: translateY(-50%); z-index: 1100; display: flex; flex-direction: column; gap: 10px; }
.frt-float-btn {
  display: flex; align-items: center; gap: 8px;
  background: linear-gradient(135deg, var(--rf-purple), var(--h-cyan));
  color: #fff; border: 0; border-radius: 999px; padding: 10px 16px;
  font-size: 14px; cursor: pointer; box-shadow: 0 6px 20px rgba(124,92,255,0.4);
  white-space: nowrap;
}
.frt-float-btn:hover { filter: brightness(1.08); }
.frt-float-btn .frt-float-ico { font-size: 16px; }

/* 名片弹层 */
.frt-card-pop {
  position: fixed; inset: 0; background: rgba(10,20,40,0.6);
  display: none; align-items: center; justify-content: center; z-index: 1200;
}
.frt-card-pop.open { display: flex; }
.frt-card-pop img { max-height: 86vh; width: auto; background: #fff; border-radius: 8px; }
.frt-card-pop .frt-card-close { position: absolute; top: 20px; right: 24px; color: #fff; font-size: 30px; cursor: pointer; }

/* ===== 首页 ===== */
.frt-hero {
  background: radial-gradient(1200px 500px at 70% -10%, rgba(124,92,255,0.25), transparent),
              linear-gradient(135deg, #0A1428, #142347);
  color: #fff; padding: 70px 24px 60px; overflow: hidden;
}
.frt-hero-inner { max-width: var(--maxw); margin: 0 auto; }
.frt-hero h1 { font-size: 40px; line-height: 1.25; margin: 0 0 16px; }
.frt-hero h1 b { color: var(--h-cyan); }
.frt-hero p { font-size: 17px; color: #c5d0e4; max-width: 720px; }
.frt-hero .frt-hero-scan { margin-top: 30px; height: 120px; width: 100%; max-width: 520px; opacity: .9; }
.frt-section { max-width: var(--maxw); margin: 50px auto; padding: 0 24px; }
.frt-section h2 { font-size: 26px; color: var(--ink); margin: 0 0 8px; }
.frt-section .frt-sec-sub { color: var(--muted); margin: 0 0 24px; }
.frt-stat-row { display: grid; grid-template-columns: repeat(auto-fit, minmax(180px,1fr)); gap: 16px; }
.frt-stat { background: var(--panel); border: 1px solid var(--line); border-radius: 14px; padding: 20px; }
.frt-stat .frt-num { font-size: 28px; font-weight: 700; color: var(--rf-purple); }
.frt-stat .frt-lbl { color: var(--muted); font-size: 14px; }
.frt-pill-row { display: flex; flex-wrap: wrap; gap: 10px; }
.frt-pill { background: var(--panel); border: 1px solid var(--line); border-radius: 999px; padding: 8px 16px; font-size: 14px; color: var(--text); }
.frt-cta { background: linear-gradient(135deg, rgba(124,92,255,0.1), rgba(24,224,200,0.1)); border: 1px solid var(--line); border-radius: 16px; padding: 30px; text-align: center; }
.frt-cta a { display: inline-block; margin-top: 14px; background: var(--rf-purple); color: #fff; padding: 12px 26px; border-radius: 999px; font-weight: 600; }
.frt-cta a:hover { background: var(--h-cyan); color: var(--ink); }

/* ===== 页脚 ===== */
.frt-foot { background: #0A1428; color: #aeb9cd; margin-top: 60px; padding: 40px 24px 30px; }
.frt-foot-inner { max-width: var(--maxw); margin: 0 auto; display: grid; grid-template-columns: 1.4fr 1fr 1fr; gap: 30px; }
.frt-foot h4 { color: #fff; font-size: 15px; margin: 0 0 12px; }
.frt-foot a { color: #aeb9cd; font-size: 14px; display: block; margin: 6px 0; }
.frt-foot a:hover { color: var(--h-cyan); }
.frt-foot .frt-copy { grid-column: 1 / -1; border-top: 1px solid rgba(255,255,255,0.1); margin-top: 20px; padding-top: 16px; font-size: 13px; color: #7b87a0; }

/* ===== 响应式（断点 1024，与契约一致） ===== */
@media (max-width: 1024px) {
  .frt-nav-sub { position: static; display: flex; box-shadow: none; border: 0; padding: 4px 0 4px 12px; }
  .frt-nav { flex-wrap: wrap; height: auto; padding: 10px 16px; }
  .frt-nav-inner { flex-wrap: wrap; }
  .frt-nav-toggle { display: block; }
  .frt-nav-menu { display: none; width: 100%; flex-direction: column; gap: 4px; padding-top: 8px; }
  .frt-nav-menu.open { display: flex; }
  .frt-nav-item { width: 100%; }
  .frt-article-layout, .frt-product-layout { grid-template-columns: 1fr; }
  .frt-toc-panel { position: static; max-height: none; }
  .frt-list-layout { grid-template-columns: 1fr; }
  .frt-cat-side { position: static; }
  .frt-hero h1 { font-size: 30px; }
  .frt-foot-inner { grid-template-columns: 1fr; }
}

/* 打印 */
@media print {
  .frt-nav, .frt-float, .frt-float-btn, .frt-card-pop, .frt-toc-panel, .frt-cat-side { display: none !important; }
}