*{margin:0;padding:0;box-sizing:border-box}
:root{
  --bg:#f8f9fa;--surface:#fff;--text:#1a1a2e;--text-secondary:#555;--border:#e2e8f0;
  --accent:#2563eb;--header-bg:#0f172a;--header-text:#f1f5f9;
  --cat-products:#2563eb;--cat-business:#059669;--cat-safety:#dc2626;
  --cat-devtools:#7c3aed;--cat-tech:#d97706;--cat-culture:#ec4899;--cat-youtube:#ff0000;
  --max-w:920px;--radius:8px;
}
body{font-family:-apple-system,BlinkMacSystemFont,"Segoe UI","Noto Sans SC",sans-serif;
  background:var(--bg);color:var(--text);line-height:1.7;font-size:15px}
a{color:var(--accent);text-decoration:none}
a:hover{text-decoration:underline}

/* Header */
.site-header{background:var(--header-bg);color:var(--header-text);padding:0}
.header-inner{max-width:var(--max-w);margin:0 auto;padding:18px 20px;display:flex;align-items:center;justify-content:space-between}
.site-title{font-size:20px;font-weight:700;letter-spacing:-0.5px}
.site-title a{color:var(--header-text)}
.site-title a:hover{text-decoration:none;opacity:.85}
.site-subtitle{font-size:12px;color:#94a3b8;margin-top:2px}
.header-date{font-size:13px;color:#94a3b8}

/* Nav */
.site-nav{background:#1e293b;border-bottom:1px solid #334155}
.nav-inner{max-width:var(--max-w);margin:0 auto;padding:0 20px;display:flex;align-items:center;gap:6px;overflow-x:auto;-webkit-overflow-scrolling:touch}
.nav-inner::-webkit-scrollbar{display:none}
.nav-link{display:inline-block;padding:10px 14px;font-size:13px;color:#cbd5e1;white-space:nowrap;border-bottom:2px solid transparent;transition:all .15s}
.nav-link:hover{color:#f1f5f9;text-decoration:none;border-bottom-color:#475569}
.nav-link.active{color:#f1f5f9;border-bottom-color:var(--accent)}

/* Main content */
.content{max-width:var(--max-w);margin:0 auto;padding:24px 20px 60px}

/* Index page */
.page-title{font-size:26px;font-weight:800;margin-bottom:6px;letter-spacing:-0.5px}
.page-desc{color:var(--text-secondary);font-size:14px;margin-bottom:28px}

.briefing-list{display:flex;flex-direction:column;gap:14px}
.briefing-card{background:var(--surface);border:1px solid var(--border);border-radius:var(--radius);padding:20px 24px;transition:box-shadow .15s}
.briefing-card:hover{box-shadow:0 2px 12px rgba(0,0,0,.06);text-decoration:none}
.card-date{font-size:13px;color:var(--text-secondary);font-weight:600;margin-bottom:4px}
.card-title{font-size:18px;font-weight:700;color:var(--text);margin-bottom:8px}
.card-meta{display:flex;flex-wrap:wrap;gap:6px;margin-bottom:10px}
.card-stat{font-size:12px;color:var(--text-secondary);background:#f1f5f9;padding:2px 10px;border-radius:12px}
.card-tags{display:flex;flex-wrap:wrap;gap:5px}
.tag{font-size:11px;padding:2px 10px;border-radius:12px;font-weight:500}
.tag-products{background:#dbeafe;color:var(--cat-products)}
.tag-business{background:#d1fae5;color:var(--cat-business)}
.tag-safety{background:#fee2e2;color:var(--cat-safety)}
.tag-devtools{background:#ede9fe;color:var(--cat-devtools)}
.tag-tech{background:#fef3c7;color:var(--cat-tech)}
.tag-culture{background:#fce7f3;color:var(--cat-culture)}
.tag-youtube{background:#fee2e2;color:var(--cat-youtube)}

/* Briefing page */
.briefing-header{margin-bottom:28px;padding-bottom:20px;border-bottom:1px solid var(--border)}
.briefing-title{font-size:24px;font-weight:800;margin-bottom:6px}
.briefing-meta{font-size:13px;color:var(--text-secondary);line-height:1.8}
.briefing-meta span{display:inline-block;margin-right:14px}
.back-link{display:inline-block;margin-bottom:16px;font-size:13px;color:var(--text-secondary)}
.back-link:hover{color:var(--accent)}

.section-title{font-size:20px;font-weight:700;margin:32px 0 16px;padding-bottom:8px;border-bottom:2px solid var(--border)}
.section-title.cat-products{border-bottom-color:var(--cat-products)}
.section-title.cat-business{border-bottom-color:var(--cat-business)}
.section-title.cat-safety{border-bottom-color:var(--cat-safety)}
.section-title.cat-devtools{border-bottom-color:var(--cat-devtools)}
.section-title.cat-tech{border-bottom-color:var(--cat-tech)}
.section-title.cat-culture{border-bottom-color:var(--cat-culture)}
.section-title.cat-youtube{border-bottom-color:var(--cat-youtube)}

.item{background:var(--surface);border:1px solid var(--border);border-radius:var(--radius);padding:16px 20px;margin-bottom:12px}
.item-title{font-size:16px;font-weight:700;margin-bottom:6px}
.item-source{font-size:12px;color:var(--text-secondary);margin-bottom:6px}
.item-source .src-badge{display:inline-block;padding:1px 7px;border-radius:4px;font-size:11px;font-weight:600;margin-right:4px}
.src-twitter{background:#e0f2fe;color:#0284c7}
.src-hn{background:#fef3c7;color:#b45309}
.src-web{background:#f1f5f9;color:#475569}
.src-youtube{background:#fee2e2;color:#dc2626}
.item-desc{font-size:14px;color:var(--text);margin-bottom:8px}
.item-links{font-size:13px}
.item-links a{margin-right:12px}

.signal-table{width:100%;border-collapse:collapse;font-size:13px;margin-top:12px}
.signal-table th{text-align:left;padding:8px 10px;background:#f8fafc;border-bottom:2px solid var(--border);font-weight:600}
.signal-table td{padding:8px 10px;border-bottom:1px solid var(--border)}

.deepdive{background:#f8fafc;border:1px solid var(--border);border-radius:var(--radius);padding:16px 20px;margin-top:8px}
.deepdive li{margin-bottom:6px;font-size:14px}

/* YouTube section */
.yt-list{list-style:none}
.yt-list li{padding:8px 0;border-bottom:1px solid var(--border);font-size:14px}
.yt-list li:last-child{border-bottom:none}
.yt-channel{font-weight:600;color:var(--cat-youtube)}

/* Footer */
.site-footer{background:#1e293b;color:#94a3b8;padding:0;margin-top:40px}
.footer-inner{max-width:var(--max-w);margin:0 auto;padding:20px;display:flex;justify-content:space-between;align-items:center;flex-wrap:wrap;gap:10px;font-size:12px}
.footer-inner a{color:#cbd5e1}

/* Responsive */
@media(max-width:640px){
  .header-inner{flex-direction:column;align-items:flex-start;gap:4px}
  .briefing-title{font-size:20px}
  .page-title{font-size:22px}
  .item{padding:14px 16px}
  .footer-inner{flex-direction:column;align-items:flex-start}
  .signal-table{font-size:12px}
  .signal-table th,.signal-table td{padding:6px}
}