/* ============================================
   科技人 - 公共样式表 (common.css)
   ============================================ */
*{margin:0;padding:0;box-sizing:border-box}
body{font-family:-apple-system,BlinkMacSystemFont,"PingFang SC","Hiragino Sans GB","Microsoft YaHei",sans-serif;color:#1f2937;background:#f9fafb;line-height:1.6;transition:background .3s,color .3s}
a{color:#2563eb;text-decoration:none}
a:hover{text-decoration:underline}
.container{max-width:1200px;margin:0 auto;padding:0 20px}

/* ===== Topbar / Navigation ===== */
.topbar{background:#fff;border-bottom:1px solid #e5e7eb;position:sticky;top:0;z-index:50;transition:background .3s,border-color .3s}
.topbar-inner{display:flex;align-items:center;justify-content:space-between;height:64px;position:relative}
.logo{font-size:20px;font-weight:700;color:#111827;display:flex;align-items:center;gap:8px;text-decoration:none}
.logo:hover{text-decoration:none}
.logo span{background:linear-gradient(135deg,#667eea,#764ba2);-webkit-background-clip:text;-webkit-text-fill-color:transparent}
.menu-btn{display:none;font-size:24px;background:none;border:none;color:#374151;cursor:pointer;padding:4px 8px}
.nav{display:flex;gap:24px;align-items:center;flex:1;justify-content:center}
.nav a{color:#4b5563;font-size:14px;font-weight:500;padding:6px 0;border-bottom:2px solid transparent;transition:all .2s;text-decoration:none}
.nav a.active{color:#2563eb;border-color:#2563eb}
.nav a:hover{color:#2563eb;text-decoration:none}
.nav-advanced{background:#6366f1;color:#fff!important;padding:6px 16px;border-radius:6px;font-size:13px!important;border-bottom:none!important}
.nav-advanced:hover{background:#4f46e5!important}
.theme-toggle{background:none;border:none;cursor:pointer;font-size:18px;padding:6px;border-radius:6px;margin-left:8px;transition:background .2s}
.theme-toggle:hover{background:#f3f4f6}
.search-form{display:flex;gap:8px;align-items:center}
.search-input{padding:8px 14px;border:1px solid #d1d5db;border-radius:20px;font-size:13px;width:200px;outline:none;transition:border-color .2s}
.search-input:focus{border-color:#667eea}
.search-btn{padding:8px 16px;background:#2563eb;color:#fff;border:none;border-radius:20px;font-size:13px;cursor:pointer;font-weight:500}
.search-btn:hover{background:#1d4ed8}

/* ===== Footer ===== */
.footer{background:#1f2937;color:#9ca3af;padding:48px 0 24px;margin-top:80px;transition:background .3s}
.footer-grid{display:grid;grid-template-columns:repeat(auto-fit,minmax(200px,1fr));gap:40px;margin-bottom:32px}
.footer h4{color:#fff;font-size:14px;margin-bottom:16px}
.footer a{color:#9ca3af;font-size:13px;display:block;padding:4px 0;text-decoration:none}
.footer a:hover{color:#fff;text-decoration:none}
.footer p{color:#9ca3af}
.footer-legal{text-align:center;padding:16px 0;border-top:1px solid #374151;font-size:12px;margin-bottom:8px}
.footer-legal a{color:#9ca3af;display:inline;margin:0 8px;font-size:12px}
.footer-legal a:hover{color:#fff}
.footer-legal span{color:#4b5563}
.copyright{text-align:center;padding-top:16px;font-size:12px;line-height:1.8}
.copyright a{color:#9ca3af;display:inline}
.copyright a:hover{color:#fff}

/* ===== Buttons ===== */
.btn{display:inline-block;padding:8px 20px;border-radius:8px;font-size:14px;font-weight:500;cursor:pointer;border:none;transition:all .2s;text-decoration:none}
.btn-primary{background:#2563eb;color:#fff}
.btn-primary:hover{background:#1d4ed8;text-decoration:none;color:#fff}
.btn-outline{background:#fff;color:#2563eb;border:1px solid #2563eb}
.btn-outline:hover{background:#2563eb;color:#fff;text-decoration:none}
.btn-accent{background:linear-gradient(135deg,#667eea,#764ba2);color:#fff}
.btn-accent:hover{opacity:.9;text-decoration:none;color:#fff}

/* ===== Sections & Cards ===== */
.section{padding:48px 0}
.section-title{font-size:22px;font-weight:700;margin-bottom:24px;display:flex;align-items:center;gap:8px}
.tag{display:inline-block;padding:3px 10px;background:#eff6ff;color:#2563eb;border-radius:12px;font-size:12px;font-weight:500}
.tag-green{background:#ecfdf5;color:#10b981}
.tag-gray{background:#f3f4f6;color:#6b7280}
.tag-orange{background:#fff7ed;color:#ea580c}
.tag-purple{background:#f5f3ff;color:#7c3aed}
.tag-amber{background:#fffbeb;color:#d97706}
.tag-blue{background:#eff6ff;color:#2563eb}
.tag-red{background:#fef2f2;color:#dc2626}
.card{background:#fff;border-radius:12px;padding:20px;box-shadow:0 1px 3px rgba(0,0,0,.06);transition:all .3s;border:1px solid transparent}
.card:hover{transform:translateY(-4px);box-shadow:0 12px 24px rgba(0,0,0,.1)}
.grid{display:grid;gap:20px}
.grid-2{grid-template-columns:repeat(2,1fr)}
.grid-3{grid-template-columns:repeat(3,1fr)}
.grid-4{grid-template-columns:repeat(4,1fr)}
.grid-5{grid-template-columns:repeat(5,1fr)}

/* ===== Pagination ===== */
.pagination{display:flex;justify-content:center;gap:6px;margin-top:40px;flex-wrap:wrap}
.pagination a{padding:10px 16px;background:#fff;border:1px solid #e5e7eb;border-radius:8px;font-size:14px;color:#4b5563;text-decoration:none;transition:all .2s}
.pagination a:hover{background:#667eea;color:#fff;border-color:#667eea}
.pagination a.active{background:#667eea;color:#fff;border-color:#667eea;font-weight:600}
.pagination .disabled{padding:10px 16px;background:#f9fafb;border:1px solid #e5e7eb;border-radius:8px;font-size:14px;color:#9ca3af}

/* ===== Empty State ===== */
.empty-state{text-align:center;padding:80px 20px;background:#fff;border-radius:16px}
.empty-icon{font-size:64px;margin-bottom:16px;opacity:.4}
.empty-text{color:#6b7280;font-size:15px}

/* ===== Toast ===== */
.toast{position:fixed;top:50%;left:50%;transform:translate(-50%,-50%);background:rgba(0,0,0,.8);color:#fff;padding:12px 24px;border-radius:8px;z-index:9999;font-size:14px;pointer-events:none;animation:toastIn .3s ease}
@keyframes toastIn{from{opacity:0;transform:translate(-50%,-50%) scale(.9)}to{opacity:1;transform:translate(-50%,-50%) scale(1)}}
.toast.success{background:rgba(16,185,129,.9)}
.toast.error{background:rgba(239,68,68,.9)}

/* ===== Breadcrumb ===== */
.breadcrumb{padding:16px 0 0;font-size:13px;color:#94a3b8}
.breadcrumb a{color:#94a3b8;transition:color .15s;text-decoration:none}
.breadcrumb a:hover{color:#6366f1}

/* ===== Lazy Load Image ===== */
img.lazy{opacity:0;transition:opacity .4s}
img.lazy.loaded{opacity:1}

/* ===== Utility Classes ===== */
.text-center{text-align:center}
.text-muted{color:#94a3b8}
.mb-0{margin-bottom:0}
.mb-1{margin-bottom:8px}
.mb-2{margin-bottom:16px}
.mb-3{margin-bottom:24px}
.mt-2{margin-top:16px}
.mt-3{margin-top:24px}
.hidden{display:none!important}
.flex{display:flex}
.flex-center{display:flex;align-items:center;justify-content:center}
.flex-between{display:flex;align-items:center;justify-content:space-between}
.flex-wrap{flex-wrap:wrap}
.gap-1{gap:8px}
.gap-2{gap:16px}
.gap-3{gap:24px}

/* ===== Dark Mode ===== */
body.dark{background:#0f172a;color:#e2e8f0}
body.dark .topbar{background:#1e293b;border-color:#334155}
body.dark .logo{color:#f1f5f9}
body.dark .nav a{color:#94a3b8}
body.dark .nav a:hover{color:#818cf8}
body.dark .nav a.active{color:#818cf8;border-color:#818cf8}
body.dark .menu-btn{color:#cbd5e1}
body.dark .search-input{background:#334155;border-color:#475569;color:#e2e8f0}
body.dark .card{background:#1e293b;border-color:#334155;box-shadow:0 1px 3px rgba(0,0,0,.3)}
body.dark .footer{background:#0f172a;border-top:1px solid #1e293b}
body.dark .tag{background:#1e3a5f;color:#93c5fd}
body.dark .tag-green{background:#052e16;color:#86efac}
body.dark .tag-orange{background:#451a03;color:#fdba74}
body.dark .tag-purple{background:#2e1065;color:#d8b4fe}
body.dark .tag-gray{background:#334155;color:#94a3b8}
body.dark .tag-amber{background:#451a03;color:#fcd34d}
body.dark .tag-blue{background:#1e3a5f;color:#93c5fd}
body.dark .btn-outline{background:transparent;color:#818cf8;border-color:#818cf8}
body.dark .pagination a{background:#1e293b;border-color:#334155;color:#94a3b8}
body.dark .empty-state{background:#1e293b}
body.dark .empty-text{color:#94a3b8}
body.dark .text-muted{color:#64748b}
body.dark .search-form .search-input{background:#334155;color:#e2e8f0}
body.dark h1,body.dark h2,body.dark h3,body.dark h4{color:#f1f5f9}

/* ===== Responsive ===== */
@media(max-width:1024px){
    .grid-4{grid-template-columns:repeat(3,1fr)}
    .grid-5{grid-template-columns:repeat(3,1fr)}
}
@media(max-width:768px){
    .grid-3,.grid-4,.grid-5{grid-template-columns:repeat(2,1fr)}
    .search-input{width:120px}
    .nav{gap:12px}
    .nav a{font-size:12px}
    .footer{padding:24px 0 20px;margin-top:40px}
    .footer-grid{display:none}
    .copyright{padding-top:0;border-top:none;font-size:11px}
}
@media(max-width:700px){
    .menu-btn{display:block}
    .nav{position:absolute;top:64px;left:0;right:0;background:#fff;border-bottom:1px solid #e5e7eb;flex-direction:column;gap:0;padding:12px 0;display:none;box-shadow:0 4px 12px rgba(0,0,0,.08)}
    body.dark .nav{background:#1e293b;border-color:#334155}
    .nav.mobile-open{display:flex}
    .nav a{padding:12px 20px;width:100%;text-align:left;border-bottom:none;border-left:3px solid transparent}
    .nav a.active{border-left-color:#2563eb;color:#2563eb}
    .nav-advanced{width:auto;margin:8px 20px 0;padding:10px 20px;text-align:center}
    .search-form{display:none}
    .theme-toggle{position:absolute;right:48px;top:16px}
}
@media(max-width:540px){
    .grid-3,.grid-4,.grid-2,.grid-5{grid-template-columns:1fr}
}