/* std- 站点样式：射频衰减器标准库（墨蓝 + 信号蓝 + 溯源青） */
:root{
  --std-ink:#0B1426;
  --std-panel:#13233F;
  --std-panel2:#0F1C34;
  --std-signal:#3E7BFA;
  --std-trace:#19C9A3;
  --std-line:#243A5E;
  --std-text:#E6EDF7;
  --std-muted:#9FB2CC;
  --std-h2-inset:24px;
  --std-nav-h:64px;
}
*{box-sizing:border-box}
html{scroll-behavior:smooth}
body{
  margin:0;background:linear-gradient(180deg,#0B1426 0%,#0E1A30 100%);
  color:var(--std-text);font-family:"Segoe UI","PingFang SC","Microsoft YaHei",system-ui,sans-serif;
  font-size:16px;line-height:1.75;padding-top:var(--std-nav-h);
}
a{color:var(--std-signal);text-decoration:none}
a:hover{text-decoration:underline}
img{max-width:100%}

/* ===== 导航 ===== */
.std-nav{position:fixed;top:0;left:0;right:0;height:var(--std-nav-h);z-index:50;
  background:rgba(11,20,38,.92);backdrop-filter:blur(8px);border-bottom:1px solid var(--std-line)}
.std-nav-inner{max-width:1200px;margin:0 auto;height:100%;display:flex;align-items:center;
  justify-content:space-between;padding:0 24px}
.std-brand{display:flex;align-items:center;gap:10px;color:var(--std-text);font-weight:700}
.std-brand:hover{text-decoration:none}
.std-mark{display:inline-flex;align-items:center;justify-content:center;width:36px;height:36px;
  border-radius:8px;background:linear-gradient(135deg,var(--std-signal),var(--std-trace));
  color:#fff;font-size:13px;font-weight:800;letter-spacing:.5px}
.std-brand-text{font-size:16px}
.std-nav-links{display:flex;gap:22px}
.std-nav-links a{color:var(--std-muted);font-size:15px}
.std-nav-links a:hover{color:var(--std-text);text-decoration:none}
.std-nav-toggle{display:none;background:transparent;border:1px solid var(--std-line);color:var(--std-text);
  font-size:20px;border-radius:8px;width:42px;height:38px;cursor:pointer}
.std-nav-sub{display:none;flex-direction:column;background:var(--std-panel2);border-bottom:1px solid var(--std-line)}
.std-nav-sub a{padding:12px 24px;color:var(--std-muted);border-top:1px solid var(--std-line)}
body.std-nav-open .std-nav-sub{display:flex}

/* ===== 容器与面包屑对齐 ===== */
.std-container{max-width:1200px;margin:0 auto;padding:0 24px}
.std-breadcrumb{padding:18px 0 4px;font-size:13.5px;color:var(--std-muted)}
.std-breadcrumb ol{list-style:none;display:flex;flex-wrap:wrap;gap:8px;margin:0;padding:0}
.std-breadcrumb li:not(:last-child)::after{content:"›";margin-left:8px;color:#5b7196}
.std-breadcrumb a{color:var(--std-muted)}
.std-breadcrumb span{color:var(--std-text)}

/* ===== 详情页双栏 ===== */
.std-layout{display:grid;grid-template-columns:minmax(0,1fr) 240px;gap:32px;align-items:start;padding-bottom:48px}
.std-content-main{padding:8px 0 24px}
.std-content-main h1{font-size:30px;line-height:1.3;margin:6px 0 14px;color:#fff}
.std-content-main h2{font-size:22px;margin:30px 0 12px;color:#fff;padding-bottom:8px;
  border-bottom:1px solid var(--std-line)}
.std-content-main h3{font-size:18px;margin:22px 0 10px;color:var(--std-trace)}
.std-content-main p{margin:0 0 14px}
.std-content-main ul,.std-content-main ol{padding-left:22px;margin:0 0 14px}
.std-content-main li{margin:6px 0}
.std-tag-row{display:flex;flex-wrap:wrap;gap:8px;margin:0 0 12px}
.std-tag{display:inline-block;padding:3px 10px;border:1px solid var(--std-line);border-radius:999px;
  font-size:12.5px;color:var(--std-muted);background:rgba(62,123,250,.08)}
.std-update{font-size:13px;color:#7e93b5}

/* ===== 正文表格边框（覆盖全部 table，含 Markdown 裸 table） ===== */
.std-content-main table,.std-page-main table,table.std-spec{
  border-collapse:collapse;width:100%;margin:14px 0 18px;font-size:14.5px;
  border:1px solid var(--std-line)}
.std-content-main table th,.std-page-main table th,table.std-spec th{
  background:var(--std-signal);color:#fff;text-align:left;padding:9px 12px;font-weight:600}
.std-content-main table td,.std-page-main table td,table.std-spec td{
  border:1px solid var(--std-line);padding:8px 12px;color:var(--std-text)}
.std-content-main table tr:nth-child(even) td,.std-page-main table tr:nth-child(even) td,
table.std-spec tr:nth-child(even) td{background:rgba(36,58,94,.35)}
.std-content-main blockquote,.std-page-main blockquote{
  border-left:3px solid var(--std-trace);margin:14px 0;padding:8px 16px;
  background:rgba(25,201,163,.07);color:var(--std-muted);border-radius:0 8px 8px 0}
.std-content-main code,.std-page-main code{background:rgba(62,123,250,.14);padding:1px 6px;border-radius:4px}
.std-content-main hr{border:none;border-top:1px solid var(--std-line);margin:20px 0}

/* ===== TOC 悬浮目录 ===== */
.std-toc-aside{position:sticky;top:calc(var(--std-nav-h) + 16px);align-self:start}
.std-toc-panel{background:var(--std-panel);border:1px solid var(--std-line);border-radius:10px;padding:10px 14px}
.std-toc-panel summary{cursor:pointer;font-weight:600;color:#fff;list-style:none;padding:4px 0}
.std-toc-panel summary::-webkit-details-marker{display:none}
.std-toc-panel summary::after{content:"▾";float:right;color:var(--std-trace)}
.std-toc-panel[open] summary::after{content:"▴"}
.std-toc-panel ol{list-style:none;margin:8px 0 0;padding:0}
.std-toc-panel li{margin:6px 0;font-size:13.5px}
.std-toc-panel a{color:var(--std-muted)}
.std-toc-panel a:hover{color:var(--std-trace);text-decoration:none}

/* ===== FAQ / 相关阅读 ===== */
.std-faq{margin-top:26px;border-top:1px solid var(--std-line);padding-top:14px}
.std-faq-title{font-size:20px;color:#fff;margin:6px 0 12px}
.std-faq details{border:1px solid var(--std-line);border-radius:8px;margin:8px 0;background:var(--std-panel2)}
.std-faq summary{cursor:pointer;padding:12px 14px;font-weight:600;color:#fff;list-style:none}
.std-faq summary::-webkit-details-marker{display:none}
.std-faq summary::after{content:"＋";float:right;color:var(--std-trace)}
.std-faq details[open] summary::after{content:"－"}
.std-faq-a{padding:0 14px 12px;color:var(--std-muted)}
.std-related{margin-top:26px;border-top:1px solid var(--std-line);padding-top:14px}
.std-related-title{font-size:20px;color:#fff;margin:6px 0 12px}
.std-related ul{list-style:none;padding:0}
.std-related li{margin:10px 0;padding-left:0}
.std-rel-why{display:block;font-size:13px;color:#7e93b5;margin-top:2px}

/* ===== 列表/分类页 ===== */
.std-list-layout{display:grid;grid-template-columns:240px minmax(0,1fr);gap:28px;
  align-items:start;padding-bottom:48px}
.std-cat-side{position:sticky;top:calc(var(--std-nav-h) + 16px);align-self:start}
.std-cat-panel{background:var(--std-panel);border:1px solid var(--std-line);border-radius:10px;padding:10px 14px}
.std-cat-panel summary{cursor:pointer;font-weight:600;color:#fff;list-style:none;padding:4px 0}
.std-cat-panel summary::-webkit-details-marker{display:none}
.std-cat-panel summary::after{content:"▾";float:right;color:var(--std-trace)}
.std-cat-panel[open] summary::after{content:"▴"}
.std-category-list{list-style:none;margin:10px 0 0;padding:0}
.std-category-list li{margin:4px 0}
.std-category-list a{display:flex;justify-content:space-between;align-items:center;
  padding:8px 10px;border-radius:8px;color:var(--std-muted)}
.std-category-list a:hover{background:rgba(62,123,250,.12);color:#fff;text-decoration:none}
.std-cat-count{font-size:12px;color:#5b7196}
.std-list-title{font-size:26px;color:#fff;margin:0 0 8px}
.std-list-intro{color:var(--std-muted);margin:0 0 18px}
.std-item-list{list-style:none;margin:0;padding:0}
.std-item{border:1px solid var(--std-line);border-radius:10px;padding:16px 18px;margin:12px 0;
  background:var(--std-panel)}
.std-item-title{font-size:18px;font-weight:600;color:#fff}
.std-item-meta{display:inline-block;margin-left:10px;font-size:12px;color:var(--std-trace);
  border:1px solid var(--std-line);border-radius:999px;padding:1px 8px}
.std-item-summary{color:var(--std-muted);margin:8px 0 0}

/* ===== 页面（叶子页） ===== */
.std-page-layout{padding-bottom:48px}
.std-page-main{padding:8px 0 24px;max-width:860px}
.std-page-main h1{font-size:30px;color:#fff;margin:6px 0 16px}
.std-page-main h2{font-size:22px;color:#fff;margin:26px 0 10px;border-bottom:1px solid var(--std-line);padding-bottom:6px}
.std-page-main h3{font-size:18px;color:var(--std-trace);margin:18px 0 8px}
.std-archive-list{list-style:none;padding:0}
.std-archive-list li{border-bottom:1px solid var(--std-line);padding:12px 0}
.std-archive-list a{font-size:17px;font-weight:600;color:#fff}
.std-archive-list p{color:var(--std-muted);margin:4px 0 0}

/* ===== 首页 ===== */
.std-hero{background:radial-gradient(1200px 400px at 70% -10%,rgba(62,123,250,.22),transparent),
  linear-gradient(180deg,#0C1730,#0B1426);border-bottom:1px solid var(--std-line)}
.std-hero-inner{max-width:1200px;margin:0 auto;padding:56px 24px 44px}
.std-hero-kicker{color:var(--std-trace);font-size:13px;letter-spacing:2px;font-weight:700}
.std-hero h1{font-size:40px;line-height:1.2;margin:12px 0 16px;color:#fff}
.std-hero p{max-width:760px;color:var(--std-muted);font-size:17px}
.std-cta{display:flex;gap:14px;flex-wrap:wrap;margin-top:24px}
.std-btn{display:inline-block;padding:11px 22px;border-radius:10px;font-weight:600;font-size:15px}
.std-btn-primary{background:linear-gradient(135deg,var(--std-signal),var(--std-trace));color:#fff}
.std-btn-primary:hover{text-decoration:none;filter:brightness(1.08)}
.std-btn-ghost{border:1px solid var(--std-line);color:var(--std-text)}
.std-btn-ghost:hover{text-decoration:none;border-color:var(--std-signal);color:#fff}
.std-stats{max-width:1200px;margin:0 auto;padding:26px 24px;display:grid;
  grid-template-columns:repeat(5,1fr);gap:14px}
.std-stat{background:var(--std-panel);border:1px solid var(--std-line);border-radius:12px;
  padding:16px;text-align:center}
.std-stat b{display:block;font-size:20px;color:#fff}
.std-stat span{font-size:13px;color:var(--std-muted)}
.std-section{max-width:1200px;margin:0 auto;padding:30px 24px}
.std-section-head{margin-bottom:18px}
.std-kicker{color:var(--std-trace);font-size:12px;letter-spacing:2px;font-weight:700}
.std-section-head h2{font-size:26px;color:#fff;margin:6px 0 6px}
.std-section-head p{color:var(--std-muted);margin:0}
.std-card-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:16px}
.std-card{background:var(--std-panel);border:1px solid var(--std-line);border-radius:12px;padding:18px;
  transition:border-color .2s,transform .2s}
.std-card:hover{border-color:var(--std-signal);transform:translateY(-3px)}
.std-card h3{font-size:17px;margin:0 0 8px}
.std-card h3 a{color:#fff}
.std-card p{color:var(--std-muted);margin:0;font-size:14.5px}

/* ===== 悬浮胶囊 ===== */
.std-float{position:fixed;right:16px;top:50%;transform:translateY(-50%);z-index:60;
  display:flex;flex-direction:column;gap:10px}
.std-float button,.std-float a{display:flex;flex-direction:column;align-items:center;justify-content:center;
  width:60px;height:60px;border:none;border-radius:14px;cursor:pointer;
  background:linear-gradient(135deg,var(--std-signal),var(--std-trace));color:#fff;
  font-size:11px;gap:2px;box-shadow:0 6px 18px rgba(0,0,0,.35)}
.std-float-ico{font-size:18px;line-height:1}
.std-float a{text-decoration:none}
.std-float button:hover,.std-float a:hover{filter:brightness(1.1)}
.std-float-card{position:fixed;right:88px;top:50%;transform:translateY(-50%);z-index:61;
  display:none;background:#0B1426;border:1px solid var(--std-line);border-radius:10px;padding:8px;
  box-shadow:0 10px 30px rgba(0,0,0,.5)}
.std-float-card.show{display:block}
.std-float-card img{display:block;width:300px;height:500px;object-fit:contain;border-radius:6px}

/* ===== 页脚 ===== */
.std-footer{background:var(--std-panel2);border-top:1px solid var(--std-line);margin-top:20px}
.std-footer-inner{max-width:1200px;margin:0 auto;padding:34px 24px;display:grid;
  grid-template-columns:2fr 1fr 1fr;gap:24px}
.std-foot-brand{font-size:18px;font-weight:700;color:#fff;margin-bottom:10px}
.std-foot-col p{color:var(--std-muted);font-size:14px}
.std-foot-col h4{color:#fff;font-size:15px;margin:0 0 10px}
.std-foot-col a{display:block;color:var(--std-muted);font-size:14px;margin:6px 0}
.std-foot-col a:hover{color:var(--std-trace);text-decoration:none}
.std-footer-bottom{max-width:1200px;margin:0 auto;padding:14px 24px;color:#6f85a8;
  font-size:13px;border-top:1px solid var(--std-line)}

/* ===== 响应式 ===== */
@media (max-width:1024px){
  .std-nav-links{display:none}
  .std-nav-toggle{display:block}
  .std-layout{grid-template-columns:1fr;gap:0}
  .std-toc-aside{position:static;top:auto;margin:0 0 18px}
  .std-list-layout{grid-template-columns:1fr}
  .std-cat-side{position:static;top:auto;margin:0 0 18px}
  .std-stats{grid-template-columns:repeat(2,1fr)}
  .std-card-grid{grid-template-columns:1fr 1fr}
  .std-footer-inner{grid-template-columns:1fr}
  .std-float{right:10px}
}
@media (max-width:640px){
  .std-hero h1{font-size:30px}
  .std-stats{grid-template-columns:1fr}
  .std-card-grid{grid-template-columns:1fr}
  .std-float button,.std-float a{width:50px;height:50px}
  .std-float-card img{width:220px;height:367px}
}