*,*::before,*::after{box-sizing:border-box}
html{scroll-behavior:smooth}
body{margin:0;font-family:"PingFang SC","Microsoft YaHei",sans-serif;color:#242424;background:#fff;line-height:1.75}
img{display:block;max-width:100%;height:auto}
a{color:#0d6efd;text-decoration:none}
a:hover{text-decoration:underline}

.split-app{display:flex;min-height:100vh;background:#fff}
.split-nav{
  width:200px;flex-shrink:0;background:#fafafa;border-right:1px solid #e5e7eb;
  position:fixed;top:0;left:0;bottom:0;overflow-y:auto;z-index:100;padding:16px 0
}
.nav-brand{display:flex;align-items:center;gap:8px;padding:0 14px 14px;border-bottom:1px solid #e5e7eb;margin-bottom:10px;font-weight:800;font-size:13px;color:#111;line-height:1.3}
.nav-brand img{width:32px;border-radius:7px;flex-shrink:0}
.nav-group{padding:6px 14px 3px;font-size:10px;font-weight:700;letter-spacing:.06em;color:#9ca3af;text-transform:uppercase}
.nav-links a{display:block;padding:7px 14px;font-size:13px;color:#4b5563;border-left:3px solid transparent;line-height:1.4}
.nav-links a:hover{background:#f3f4f6;color:#111;text-decoration:none}
.nav-links a.active{background:#eff6ff;color:#0d6efd;border-left-color:#0d6efd;font-weight:600}

.split-body{flex:1;margin-left:200px;min-width:0;display:flex;flex-direction:column}
.split-top{display:none;align-items:center;gap:10px;padding:10px 14px;border-bottom:1px solid #e5e7eb;background:#fff;position:sticky;top:0;z-index:50}
.nav-toggle{border:1px solid #d1d5db;background:#fff;border-radius:8px;padding:7px 11px;font-size:17px;cursor:pointer;line-height:1}
.split-top-title{font-weight:700;font-size:14px;color:#111}

.split-content{width:min(780px,calc(100% - 40px));margin:0 auto;padding:28px 0 44px;flex:1}
.split-content.wide{width:min(900px,calc(100% - 40px))}

.split-content h1{font-size:clamp(24px,2.8vw,32px);line-height:1.3;margin:0 0 14px;color:#111}
.split-content h2{font-size:20px;margin:32px 0 10px;padding-top:6px;border-top:1px solid #f0f0f0;color:#111}
.split-content h2:first-of-type{border-top:none;padding-top:0;margin-top:20px}
.split-content h3{font-size:16px;margin:22px 0 8px;color:#333}
.split-content p,.split-content li{font-size:15px;color:#444}
.split-content ul,.split-content ol{padding-left:20px}
.lead{font-size:16px;color:#374151;margin-bottom:20px}
.meta{font-size:12px;color:#9ca3af;margin-bottom:24px}

.note{margin:20px 0;padding:14px 16px;background:#f0f7ff;border:1px solid #bfdbfe;border-radius:8px;font-size:14px;color:#1e40af}
.note-warn{background:#fffbeb;border-color:#fde68a;color:#92400e}

.ext-row{display:flex;flex-wrap:wrap;gap:10px;margin:20px 0}
.ext-chip{display:inline-block;padding:8px 14px;border:1px solid #dbeafe;background:#eff6ff;border-radius:999px;font-size:13px;color:#1d4ed8}
.ext-chip:hover{background:#dbeafe;text-decoration:none}

.preview-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:14px;margin:22px 0}
.preview-card{border:1px solid #e5e7eb;border-radius:9px;overflow:hidden;background:#fff}
.preview-card img{aspect-ratio:2/3;object-fit:cover;width:100%}
.preview-card figcaption{padding:10px 12px;font-size:12px;color:#555}
.preview-card strong{display:block;color:#111;font-size:13px;margin-bottom:3px}

.two-col{display:grid;grid-template-columns:1fr 1fr;gap:16px;margin:22px 0}
.panel{border:1px solid #e5e7eb;border-radius:9px;padding:16px;background:#fafafa}
.panel h3{margin:0 0 6px;font-size:15px}

.hero-img{border:1px solid #e5e7eb;border-radius:9px;overflow:hidden;margin:22px 0}
.hero-img img{width:100%;max-height:340px;object-fit:cover}

.shot-row{display:grid;grid-template-columns:1fr 1fr;gap:14px;margin:22px 0}
.shot-row img{border:1px solid #e5e7eb;border-radius:9px}

.faq details{border:1px solid #e5e7eb;border-radius:8px;padding:12px 16px;margin-bottom:8px;background:#fff}
.faq summary{cursor:pointer;font-weight:600;color:#111;list-style:none}
.faq summary::-webkit-details-marker{display:none}
.faq p{margin:8px 0 0;font-size:14px;color:#555}

.related{margin-top:28px;padding-top:18px;border-top:1px solid #e5e7eb}
.related h3{font-size:15px;margin:0 0 10px}
.related ul{margin:0;padding-left:18px;font-size:14px}

.split-foot{padding:20px 20px 28px;border-top:1px solid #e5e7eb;font-size:12px;color:#9ca3af;margin-top:auto}
.split-foot a{color:#6b7280;margin-right:14px}
.split-foot p{margin:8px 0 0}

.nav-overlay{display:none;position:fixed;inset:0;background:rgba(0,0,0,.35);z-index:90}
.nav-overlay.on{display:block}

.err-wrap{min-height:60vh;display:grid;place-items:center;text-align:center;padding:36px 18px}
.err-wrap h1{font-size:44px;margin:0 0 10px;color:#111}

@media(max-width:860px){
  .split-nav{transform:translateX(-100%);transition:transform .25s ease}
  .split-nav.open{transform:translateX(0);box-shadow:4px 0 20px rgba(0,0,0,.12)}
  .split-body{margin-left:0}
  .split-top{display:flex}
  .preview-grid,.two-col,.shot-row{grid-template-columns:1fr}
}