/* ============================================================
   实用指南 — 前台主题
   设计目标：干净、可读、移动优先、无 JS 依赖
   ============================================================ */

:root{
  --bg:#ffffff;
  --fg:#111827;
  --fg-soft:#374151;
  --muted:#6b7280;
  --line:#e6e8ec;
  --line-soft:#f1f3f6;
  --brand:#2563eb;
  --brand-d:#1d4ed8;
  --chip:#eef2ff;
  --soft:#f8fafc;
  --maxw:1120px;
  --radius:14px;
  --shadow:0 1px 2px rgba(16,24,40,.04), 0 6px 20px rgba(16,24,40,.06);
  --header-h:62px;
}

*,*::before,*::after{box-sizing:border-box}
html{-webkit-text-size-adjust:100%;scroll-behavior:smooth}
body{
  margin:0;
  font-family:-apple-system,BlinkMacSystemFont,"Segoe UI",Roboto,"PingFang SC","Hiragino Sans GB","Microsoft YaHei",sans-serif;
  color:var(--fg);background:var(--bg);
  line-height:1.75;font-size:16px;
  -webkit-font-smoothing:antialiased;
  overflow-wrap:break-word;
}
img{max-width:100%;height:auto}
a{color:var(--brand);text-decoration:none}
a:hover{text-decoration:underline}
h1,h2,h3,h4{line-height:1.35;letter-spacing:-.01em}

.wrap{max-width:var(--maxw);margin:0 auto;padding:0 18px;width:100%}

/* 无障碍：跳到主要内容 */
.skip-link{position:absolute;left:-9999px;top:0;background:var(--brand);color:#fff;padding:10px 16px;border-radius:0 0 8px 0;z-index:200}
.skip-link:focus{left:0;text-decoration:none}

/* ============================================================
   顶部导航
   ============================================================ */
.site-header{
  position:sticky;top:0;z-index:100;
  background:rgba(255,255,255,.9);
  -webkit-backdrop-filter:saturate(180%) blur(12px);
  backdrop-filter:saturate(180%) blur(12px);
  border-bottom:1px solid var(--line);
}
.header-inner{
  display:flex;align-items:center;gap:14px;
  min-height:var(--header-h);
}

.brand{display:inline-flex;align-items:center;gap:10px;flex:none;color:var(--fg);font-weight:700;font-size:18px;letter-spacing:-.01em}
.brand:hover{text-decoration:none;color:var(--brand-d)}
.brand-logo{display:block;width:32px;height:32px;border-radius:8px;flex:none}
.brand-name{white-space:nowrap}

/* 汉堡开关（纯 CSS，无 JS） */
.nav-toggle{position:absolute;width:1px;height:1px;opacity:0;pointer-events:none}
.nav-burger{display:none}

.nav-panel{display:flex;align-items:center;gap:12px;flex:1;justify-content:flex-end;min-width:0}
.site-nav{display:flex;align-items:center;gap:2px;min-width:0}
.nav-link{
  display:block;padding:8px 11px;border-radius:9px;
  color:var(--fg-soft);font-size:15px;line-height:1.4;white-space:nowrap;
  transition:background .15s,color .15s;
}
.nav-link:hover{background:var(--chip);color:var(--brand-d);text-decoration:none}
.nav-link.active{background:var(--brand);color:#fff}
.nav-link.active:hover{background:var(--brand-d);color:#fff}

/* 搜索框 */
.search{position:relative;display:flex;align-items:center;flex:none}
.search input{
  width:158px;padding:8px 36px 8px 14px;
  border:1px solid var(--line);border-radius:999px;
  font-size:14px;background:var(--soft);color:var(--fg);
  outline:none;transition:width .2s,border-color .15s,box-shadow .15s,background .15s;
  -webkit-appearance:none;appearance:none;
}
.search input::placeholder{color:#9aa1ac}
.search input:focus{width:210px;background:#fff;border-color:var(--brand);box-shadow:0 0 0 3px rgba(37,99,235,.13)}
.search button{
  position:absolute;right:3px;top:50%;transform:translateY(-50%);
  width:30px;height:30px;display:flex;align-items:center;justify-content:center;
  border:0;background:none;color:var(--muted);cursor:pointer;border-radius:50%;padding:0;
}
.search button:hover{color:var(--brand)}
.search svg{width:16px;height:16px;display:block}

/* ------- 中等宽度：导航紧凑一档，避免挤压换行 ------- */
@media (max-width:1240px){
  .nav-link{padding:8px 9px;font-size:14.5px}
  .search input{width:136px}
  .search input:focus{width:186px}
}

/* ------- 移动端：汉堡抽屉 ------- */
@media (max-width:1100px){
  .nav-burger{
    display:flex;flex-direction:column;justify-content:center;gap:5px;
    width:44px;height:44px;padding:0 11px;margin-left:auto;
    border:1px solid var(--line);border-radius:11px;background:#fff;
    cursor:pointer;flex:none;
  }
  .nav-burger span{display:block;height:2px;width:100%;background:var(--fg);border-radius:2px;transition:transform .24s,opacity .18s}
  .nav-toggle:checked ~ .nav-burger span:nth-child(1){transform:translateY(7px) rotate(45deg)}
  .nav-toggle:checked ~ .nav-burger span:nth-child(2){opacity:0}
  .nav-toggle:checked ~ .nav-burger span:nth-child(3){transform:translateY(-7px) rotate(-45deg)}
  .nav-toggle:focus-visible ~ .nav-burger{outline:2px solid var(--brand);outline-offset:2px}

  .nav-panel{
    position:absolute;left:0;right:0;top:100%;
    flex-direction:column;align-items:stretch;gap:0;
    background:#fff;border-bottom:1px solid var(--line);box-shadow:var(--shadow);
    max-height:0;overflow:hidden;
    transition:max-height .28s ease;
  }
  .nav-toggle:checked ~ .nav-panel{max-height:min(78vh,620px);overflow-y:auto}

  .site-nav{flex-direction:column;align-items:stretch;gap:0;padding:4px 0}
  .nav-link{
    padding:14px 20px;border-radius:0;font-size:16px;
    border-bottom:1px solid var(--line-soft);
    border-left:3px solid transparent;
  }
  .nav-link:hover{background:var(--soft)}
  .nav-link.active{background:var(--chip);color:var(--brand-d);border-left-color:var(--brand)}
  .nav-link.active:hover{background:var(--chip);color:var(--brand-d)}

  .search{padding:14px 20px 18px}
  .search input,.search input:focus{width:100%}
  .search button{right:24px}
}
@media (max-width:380px){
  .brand-name{font-size:16px}
}

/* ============================================================
   主体
   ============================================================ */
main.wrap{padding-top:26px;padding-bottom:36px;min-height:58vh}

/* 面包屑 */
.crumbs{display:flex;flex-wrap:wrap;align-items:center;gap:6px;font-size:13px;color:var(--muted);margin:0 0 16px}
.crumbs a{color:var(--muted)}
.crumbs a:hover{color:var(--brand)}
.crumbs .sep{opacity:.45}
.crumbs .cur{color:var(--fg-soft);overflow:hidden;text-overflow:ellipsis;white-space:nowrap;max-width:min(100%,420px)}

/* 首页 Hero */
.hero{
  background:linear-gradient(135deg,#eef4ff 0%,#f7f9fc 62%);
  border:1px solid var(--line);border-radius:18px;
  padding:clamp(24px,5vw,42px);margin-bottom:26px;
}
.hero h1{margin:0 0 10px;font-size:clamp(24px,5vw,33px)}
.hero p{margin:0;color:var(--muted);font-size:clamp(15px,2.6vw,17px);max-width:56ch}
.hero-chips{display:flex;flex-wrap:wrap;gap:8px;margin-top:18px}
.chip{
  display:inline-block;padding:7px 14px;border-radius:999px;
  background:#fff;border:1px solid var(--line);
  font-size:13.5px;color:var(--fg-soft);line-height:1.4;
  transition:border-color .15s,color .15s;
}
.chip:hover{border-color:var(--brand);color:var(--brand);text-decoration:none}

.section-head{display:flex;align-items:baseline;justify-content:space-between;gap:12px;margin:0 0 14px}
.section-head h2{font-size:19px;margin:0}
.section-head .more{font-size:14px}

/* 文章卡片网格 */
.grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(292px,1fr));gap:18px}
.card{
  display:flex;flex-direction:column;
  border:1px solid var(--line);border-radius:var(--radius);
  padding:20px;background:#fff;
  transition:transform .18s,border-color .18s,box-shadow .18s;
}
.card:hover{transform:translateY(-2px);border-color:#c7d2fe;box-shadow:var(--shadow)}
.card-cat{
  align-self:flex-start;display:inline-block;
  padding:3px 10px;border-radius:999px;background:var(--chip);
  color:var(--brand-d);font-size:12px;line-height:1.6;margin-bottom:10px;
}
.card-cat:hover{text-decoration:none;background:#e0e7ff}
.card-title{margin:0 0 8px;font-size:18px;line-height:1.5}
.card-title a{color:var(--fg)}
.card-title a:hover{color:var(--brand-d)}
.meta{color:var(--muted);font-size:13px}
.card .excerpt{margin:0 0 14px;color:var(--fg-soft);font-size:14.5px;flex:1}
.card-foot{display:flex;align-items:center;justify-content:space-between;gap:10px;margin-top:auto}
.read{font-size:14px;font-weight:600;white-space:nowrap}

.empty{border:1px dashed var(--line);border-radius:var(--radius);padding:36px 20px;text-align:center;color:var(--muted)}

/* 列表页标题 */
.page-title{font-size:clamp(22px,4.6vw,28px);margin:0 0 8px}
.lead{color:var(--muted);margin:0 0 22px;max-width:60ch}

/* ============================================================
   正文
   ============================================================ */
.post{max-width:740px;margin:0 auto}
.post h1{font-size:clamp(23px,5.2vw,34px);margin:0 0 10px}
.post > .meta{margin:0 0 22px;padding-bottom:14px;border-bottom:1px solid var(--line);font-size:14px}
.post h2{margin:34px 0 12px;font-size:clamp(19px,3.6vw,23px);padding-bottom:8px;border-bottom:1px solid var(--line-soft)}
.post h3{margin:26px 0 8px;font-size:clamp(17px,3vw,19px)}
.post p{margin:0 0 17px}
.post ul,.post ol{margin:0 0 17px;padding-left:22px}
.post li{margin:7px 0}
.post li>ul,.post li>ol{margin:7px 0}
.post strong{color:var(--fg);font-weight:600}
.post hr{border:0;border-top:1px solid var(--line);margin:30px 0}
.post img{border-radius:10px;margin:16px 0;display:block}
.post pre{
  background:#0f172a;color:#e2e8f0;padding:16px;border-radius:12px;
  overflow-x:auto;-webkit-overflow-scrolling:touch;
  font-size:13.5px;line-height:1.65;margin:0 0 18px;
}
.post code{background:#f1f5f9;padding:2px 6px;border-radius:5px;font-size:.92em;word-break:break-word}
.post pre code{background:none;padding:0;font-size:inherit;white-space:pre}
.post blockquote{
  border-left:4px solid var(--brand);margin:18px 0;padding:10px 18px;
  color:#475569;background:#f8fafc;border-radius:0 10px 10px 0;
}
.post blockquote p:last-child{margin-bottom:0}
.post table{width:100%;border-collapse:collapse;display:block;overflow-x:auto;margin:0 0 18px;font-size:14.5px}
.post th,.post td{border:1px solid var(--line);padding:9px 12px;text-align:left}
.post th{background:var(--soft);font-weight:600}

/* 上一篇 / 下一篇 */
.post-nav{display:grid;grid-template-columns:1fr 1fr;gap:12px;margin:32px auto 0;max-width:740px}
.post-nav a{
  display:block;border:1px solid var(--line);border-radius:12px;
  padding:14px 16px;color:var(--fg);transition:border-color .15s,background .15s;
}
.post-nav a:hover{border-color:var(--brand);background:var(--soft);text-decoration:none}
.post-nav .lbl{display:block;font-size:12px;color:var(--muted);margin-bottom:4px}
.post-nav .ttl{font-size:15px;line-height:1.5}
.post-nav .next{text-align:right}

/* 相关文章 */
.related{max-width:740px;margin:34px auto 0}
.related h2{font-size:19px;margin:0 0 14px}
.related ul{list-style:none;margin:0;padding:0;display:grid;gap:10px}
.related a{
  display:block;padding:13px 16px;border:1px solid var(--line);border-radius:12px;
  color:var(--fg);font-size:15px;line-height:1.5;transition:border-color .15s,background .15s;
}
.related a:hover{border-color:var(--brand);background:var(--soft);text-decoration:none}
.related .rmeta{display:block;font-size:12.5px;color:var(--muted);margin-top:3px}

@media (max-width:600px){
  .post-nav{grid-template-columns:1fr}
  .post-nav .next{text-align:left}
}

/* 广告位（默认关闭；仅内容页出现） */
.ad-slot{margin:24px 0;text-align:center;overflow:hidden}

/* ============================================================
   页脚
   ============================================================ */
.site-footer{border-top:1px solid var(--line);background:var(--soft);margin-top:48px;padding:34px 0 22px}
.footer-inner{display:grid;grid-template-columns:1.7fr 1fr 1fr;gap:28px}
.foot-brand .brand{font-size:17px}
.foot-brand p{margin:10px 0 0;color:var(--muted);font-size:14px;max-width:36ch}
.foot-col h3{margin:0 0 12px;font-size:14px;color:var(--fg);font-weight:600}
.foot-col ul{list-style:none;margin:0;padding:0;display:grid;gap:9px}
.foot-col a{color:var(--muted);font-size:14px}
.foot-col a:hover{color:var(--brand)}
.foot-bottom{
  margin-top:26px;padding-top:18px;border-top:1px solid var(--line);
  color:var(--muted);font-size:13px;
  display:flex;flex-wrap:wrap;gap:8px 18px;justify-content:space-between;
}
@media (max-width:760px){
  .footer-inner{grid-template-columns:1fr 1fr;gap:24px}
  .foot-brand{grid-column:1 / -1}
}
@media (max-width:420px){
  .footer-inner{grid-template-columns:1fr}
}

/* 触摸设备去掉 hover 位移，避免"点一下卡片跳一下" */
@media (hover:none){
  .card:hover{transform:none;box-shadow:none}
}

/* ============================================================
   语言切换器
   ============================================================ */
.lang-switch{display:inline-flex;align-items:center;border:1px solid var(--line);border-radius:999px;overflow:hidden;flex:none;background:#fff}
.lang-link{
  padding:6px 12px;font-size:13px;line-height:1.3;color:var(--fg-soft);
  border-left:1px solid var(--line);
}
.lang-link:first-child{border-left:0}
.lang-link:hover{background:var(--chip);text-decoration:none;color:var(--brand-d)}
.lang-link.active{background:var(--brand);color:#fff;font-weight:600}
.lang-link.active:hover{background:var(--brand-d);color:#fff}
@media (max-width:1100px){
  .lang-switch{margin:10px 20px 14px;align-self:flex-start}
}
/* 尊重"减少动态效果"偏好 */
@media (prefers-reduced-motion:reduce){
  *{animation-duration:.01ms !important;transition-duration:.01ms !important;scroll-behavior:auto !important}
}