:root{
  --bl-primary:#0ea5e9;--bl-primary-d:#0369a1;--bl-bg:#f0fafb;--bl-bg2:#e0f5f9;
  --bl-text:#0f172a;--bl-muted:#64748b;--bl-card:#ffffff;--bl-border:#e2e8f0;
  --bl-radius:18px;--bl-shadow:0 8px 30px rgba(14,165,233,.08);
}
* { box-sizing: border-box; }
html,body{margin:0;padding:0;}
body.bl-body{font-family:'Inter',system-ui,-apple-system,'Segoe UI',Roboto,'PingFang SC','Microsoft YaHei',sans-serif;background:linear-gradient(180deg,var(--bl-bg) 0%,#ffffff 60%);color:var(--bl-text);line-height:1.7;-webkit-font-smoothing:antialiased;min-height:100vh;display:flex;flex-direction:column;}
a{color:inherit;text-decoration:none;}
.hidden{display:none !important;}
/* top navigation — matches homepage nav */
.bl-topnav{position:fixed;top:0;left:0;right:0;z-index:50;background:rgba(255,255,255,.85);border-bottom:1px solid rgba(226,232,240,.7);backdrop-filter:blur(12px);transition:background .2s,border-color .2s;}
.bl-topnav-inner{max-width:1280px;margin:0 auto;padding:12px 20px;display:flex;align-items:center;justify-content:space-between;}
.bl-brand{display:flex;align-items:center;gap:10px;color:#0f172a;}
.bl-brand-icon{width:32px;height:32px;border-radius:8px;background:linear-gradient(135deg,#0ea5e9 0%,#0d9488 100%);display:flex;align-items:center;justify-content:center;box-shadow:0 4px 12px -3px rgba(14,165,233,.35);}
.bl-brand-icon svg{width:18px;height:18px;color:#fff;}
.bl-brand-text{font-weight:700;font-size:15px;letter-spacing:-.01em;}
.bl-topnav-links{display:none;align-items:center;gap:20px;}
@media(min-width:768px){.bl-topnav-links{display:flex;}}
.bl-site-link{font-size:.875rem;font-weight:500;color:#475569;transition:color .2s,background .2s;padding:6px 14px;border-radius:9999px;}
.bl-site-link:hover{color:#0ea5e9;background:#f0f9ff;}
.bl-site-link.active{background:#0ea5e9;color:#fff;font-weight:600;}
.bl-topnav-actions{display:flex;align-items:center;gap:16px;}
.bl-lang-wrap{position:relative;}
.bl-lang-toggle{display:flex;align-items:center;gap:4px;padding:6px 10px;border-radius:8px;border:1px solid #e2e8f0;background:#fff;color:#334155;font-size:12px;font-weight:600;cursor:pointer;transition:all .15s;}
.bl-lang-toggle:hover{border-color:#bae6fd;color:#0ea5e9;}
.bl-chevron{width:12px;height:12px;opacity:.7;}
.bl-lang-menu{position:absolute;right:0;top:calc(100% + 8px);width:140px;background:#fff;border:1px solid #e2e8f0;border-radius:12px;box-shadow:0 10px 30px rgba(15,23,42,.12);overflow:hidden;z-index:60;}
.bl-lang-btn{width:100%;text-align:left;padding:9px 14px;font-size:12px;font-weight:500;color:#334155;background:#fff;border:none;cursor:pointer;transition:background .15s,color .15s;}
.bl-lang-btn:hover{background:#f0f9ff;color:#0ea5e9;}
.bl-lang-btn.active{background:#0ea5e9;color:#fff;}
.bl-theme-toggle{width:32px;height:32px;border-radius:8px;border:1px solid #e2e8f0;background:#fff;color:#475569;display:flex;align-items:center;justify-content:center;cursor:pointer;transition:all .15s;}
.bl-theme-toggle:hover{border-color:#bae6fd;color:#0ea5e9;background:#f0f9ff;}
.bl-icon{width:16px;height:16px;}
.bl-main{max-width:920px;margin:0 auto;padding:80px 20px 48px;flex:1;width:100%;}
.bl-hero{text-align:center;padding:32px 0 12px;}
.bl-h1{font-size:34px;font-weight:800;letter-spacing:-.02em;margin:0 0 12px;}
.bl-intro{max-width:620px;margin:0 auto;color:var(--bl-muted);font-size:15px;}
.bl-grid{margin-top:28px;display:grid;grid-template-columns:repeat(auto-fill,minmax(280px,1fr));gap:18px;}
.bl-card{display:flex;flex-direction:column;background:var(--bl-card);border:1px solid var(--bl-border);border-radius:var(--bl-radius);padding:22px;transition:transform .25s cubic-bezier(.16,1,.3,1),box-shadow .25s, border-color .2s;}
.bl-card:hover{transform:translateY(-4px);box-shadow:var(--bl-shadow);border-color:var(--bl-primary);}
.bl-card-meta{display:flex;align-items:center;gap:10px;margin-bottom:10px;}
.bl-card-cat{font-size:11px;font-weight:700;letter-spacing:.04em;color:var(--bl-primary-d);background:var(--bl-bg2);padding:3px 10px;border-radius:999px;}
.bl-card-date{font-size:12px;color:var(--bl-muted);}
.bl-card-title{font-size:18px;font-weight:700;margin:0 0 8px;line-height:1.4;}
.bl-card-excerpt{font-size:13.5px;color:var(--bl-muted);margin:0 0 14px;flex:1;}
.bl-card-more{font-size:13px;font-weight:700;color:var(--bl-primary-d);display:inline-flex;gap:4px;transition:gap .2s;}
.bl-card:hover .bl-card-more{gap:9px;}
/* article */
.bl-article-wrap{max-width:760px;}
.bl-breadcrumb{font-size:13px;color:var(--bl-muted);padding:8px 0 4px;}
.bl-breadcrumb a:hover{color:var(--bl-primary);}
.bl-sep{margin:0 8px;opacity:.5;}
.bl-article{margin-top:8px;}
.bl-article-meta{display:flex;align-items:center;gap:8px;font-size:13px;color:var(--bl-muted);margin-bottom:10px;}
.bl-dot{opacity:.5;}
.bl-article-title{font-size:30px;font-weight:800;letter-spacing:-.02em;margin:0 0 20px;line-height:1.3;}
.bl-article-body{font-size:16px;color:#1e293b;}
.bl-article-body p{margin:0 0 18px;}
.bl-article-body h2{font-size:21px;font-weight:700;margin:30px 0 12px;}
.bl-article-body code{background:var(--bl-bg2);color:var(--bl-primary-d);padding:2px 7px;border-radius:6px;font-size:14px;font-family:ui-monospace,SFMono-Regular,Menlo,monospace;}
.bl-article-body strong{color:var(--bl-primary-d);}
.bl-article-byline{margin-top:28px;padding-top:18px;border-top:1px solid var(--bl-border);font-size:13px;color:var(--bl-muted);}
.bl-related{margin-top:40px;}
.bl-section-title{font-size:19px;font-weight:700;margin:0 0 16px;}
.bl-rel-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(200px,1fr));gap:14px;}
.bl-rel-card{display:flex;flex-direction:column;gap:6px;background:var(--bl-card);border:1px solid var(--bl-border);border-radius:14px;padding:16px;transition:transform .2s,box-shadow .2s,border-color .2s;}
.bl-rel-card:hover{transform:translateY(-3px);box-shadow:var(--bl-shadow);border-color:var(--bl-primary);}
.bl-rel-cat{font-size:11px;font-weight:700;color:var(--bl-primary-d);}
.bl-rel-title{font-size:14px;font-weight:600;line-height:1.4;}
.bl-rel-date{font-size:12px;color:var(--bl-muted);}
.bl-back{margin-top:36px;}
.bl-back-link{font-size:14px;font-weight:600;color:var(--bl-primary-d);}
.bl-back-link:hover{text-decoration:underline;}
.bl-footer{max-width:920px;margin:40px auto 0;padding:32px 20px;border-top:1px solid var(--bl-border);width:100%;}
.bl-footer-legal{text-align:center;font-size:13px;color:var(--bl-muted);margin-bottom:10px;}
.bl-footer-legal a:hover{color:var(--bl-primary);}
.bl-copy{text-align:center;font-size:12px;color:#94a3b8;}
.bl-disclaimer{background:rgba(14,165,233,.08);border-left:4px solid var(--bl-primary);border-radius:10px;padding:14px 16px;margin:0 0 20px;font-size:14px;color:var(--bl-primary-d);line-height:1.55;}
.bl-disclaimer strong{font-weight:700;}
@media (max-width:640px){.bl-h1{font-size:27px;}.bl-article-title{font-size:25px;}.bl-main{padding:16px 14px 40px;}.bl-grid{grid-template-columns:1fr;}}
/* dark mode */
html.dark body.bl-body{background:linear-gradient(180deg,#0b1120 0%,#0f172a 60%);}
html.dark .bl-topnav{background:rgba(15,23,42,.88);border-color:rgba(51,65,85,.7);}
html.dark .bl-brand{color:#f1f5f9;}
html.dark .bl-site-link{color:#94a3b8;}
html.dark .bl-site-link:hover{color:#38bdf8;background:rgba(14,165,233,.12);}
html.dark .bl-site-link.active{background:#0ea5e9;color:#fff;}
html.dark .bl-lang-toggle,html.dark .bl-theme-toggle{background:#0f172a;border-color:#334155;color:#cbd5e1;}
html.dark .bl-lang-toggle:hover,html.dark .bl-theme-toggle:hover{border-color:#0ea5e9;color:#38bdf8;background:#0f172a;}
html.dark .bl-lang-menu{background:#0f172a;border-color:#334155;}
html.dark .bl-lang-btn{background:#0f172a;color:#cbd5e1;}
html.dark .bl-lang-btn:hover{background:#0f172a;color:#38bdf8;}
html.dark .bl-lang-btn.active{background:#0ea5e9;color:#fff;}
html.dark .bl-article-body{color:#cbd5e1;}
html.dark .bl-footer-legal a:hover,html.dark .bl-breadcrumb a:hover,html.dark .bl-back-link:hover{color:var(--bl-primary);}
@media (prefers-color-scheme: dark){
  :root{--bl-bg:#0b1120;--bl-bg2:#142033;--bl-text:#e2e8f0;--bl-muted:#94a3b8;--bl-card:#0f172a;--bl-border:#1e293b;--bl-shadow:0 8px 30px rgba(0,0,0,.35);}
  body.bl-body{background:linear-gradient(180deg,#0b1120 0%,#0f172a 60%);}
  .bl-article-body{color:#cbd5e1;}
  .bl-footer-legal a:hover,.bl-breadcrumb a:hover,.bl-back-link:hover{color:var(--bl-primary);}
}