:root{--primary:#e63946;--primary-dark:#c1121f;--secondary:#1d3557;--accent:#457b9d;--bg:#f8f9fa;--card:#fff;--text:#1a1a2e;--text-light:#6c757d;--success:#2a9d8f;--warning:#e9c46a;--danger:#e63946;--border:#dee2e6;--shadow:0 4px 20px rgba(0,0,0,0.08);--radius:12px}
*{box-sizing:border-box;margin:0;padding:0}
html{scroll-behavior:smooth;-webkit-text-size-adjust:100%}
body{font-family:-apple-system,BlinkMacSystemFont,"Segoe UI",Roboto,"Helvetica Neue",Arial,"Noto Sans SC","PingFang SC","Microsoft YaHei",sans-serif;background:var(--bg);color:var(--text);line-height:1.6;-webkit-font-smoothing:antialiased}
a{color:var(--primary);text-decoration:none}
img{max-width:100%;height:auto;display:block}
.container{max-width:1200px;margin:0 auto;padding:0 20px}

/* Header */
header{background:linear-gradient(135deg,var(--secondary) 0%,#0f172a 100%);color:#fff;padding:0;position:sticky;top:0;z-index:1000;box-shadow:0 2px 10px rgba(0,0,0,0.2)}
.header-inner{display:flex;align-items:center;justify-content:space-between;height:64px}
.logo{display:flex;align-items:center;gap:10px;font-size:1.4rem;font-weight:700;color:#fff}
.logo img,.logo svg{width:32px;height:32px}
.nav{display:flex;gap:4px;align-items:center}
.nav a{color:rgba(255,255,255,0.85);padding:8px 12px;border-radius:6px;font-size:0.85rem;transition:all .2s;white-space:nowrap}
.nav a:hover,.nav a.active{background:rgba(255,255,255,0.15);color:#fff}
.mobile-menu-btn{display:none;background:none;border:none;color:#fff;font-size:1.5rem;cursor:pointer;padding:8px}

/* Hero */
.hero{background:linear-gradient(135deg,var(--secondary) 0%,var(--accent) 100%);color:#fff;padding:60px 0;text-align:center}
.hero h1{font-size:2.4rem;margin-bottom:16px;font-weight:700;line-height:1.3}
.hero p{font-size:1.1rem;opacity:0.9;max-width:700px;margin:0 auto 30px}
.hero-badges{display:flex;gap:12px;justify-content:center;flex-wrap:wrap}
.badge{background:rgba(255,255,255,0.15);padding:6px 16px;border-radius:20px;font-size:0.85rem}

/* Cards */
.card{background:var(--card);border-radius:var(--radius);box-shadow:var(--shadow);padding:28px;margin-bottom:24px}
.card h2{font-size:1.3rem;margin-bottom:16px;color:var(--secondary);display:flex;align-items:center;gap:8px}
.card h2 svg,.card h2 .icon{width:24px;height:24px;fill:var(--primary);display:inline-flex;align-items:center;justify-content:center}

/* Forms */
.form-grid{display:grid;grid-template-columns:repeat(auto-fit,minmax(200px,1fr));gap:16px;margin-bottom:20px}
.form-group label{display:block;margin-bottom:6px;font-weight:600;font-size:0.9rem;color:var(--text-light)}
.form-group input,.form-group select{width:100%;padding:12px 14px;border:2px solid var(--border);border-radius:8px;font-size:1rem;transition:border-color .2s;font-family:inherit;-webkit-appearance:none;appearance:none;background:#fff}
.form-group input:focus,.form-group select:focus{outline:none;border-color:var(--primary)}
.form-group select{background-image:url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='12' viewBox='0 0 12 12'%3E%3Cpath fill='%236c757d' d='M6 8L1 3h10z'/%3E%3C/svg%3E");background-repeat:no-repeat;background-position:right 12px center;padding-right:32px}
.btn{display:inline-flex;align-items:center;gap:8px;background:var(--primary);color:#fff;padding:12px 28px;border:none;border-radius:8px;font-size:1rem;font-weight:600;cursor:pointer;transition:all .2s;touch-action:manipulation;-webkit-tap-highlight-color:transparent}
.btn:hover{background:var(--primary-dark);transform:translateY(-1px)}
.btn:active{transform:translateY(0)}
.btn-secondary{background:var(--accent)}
.btn-secondary:hover{background:#3d6a8a}
.btn-success{background:var(--success)}

/* Results */
.result-box{background:#f1f5f9;border-radius:10px;padding:20px;margin-top:20px;display:none}
.result-box.active{display:block;animation:fadeIn .3s}
@keyframes fadeIn{from{opacity:0;transform:translateY(10px)}to{opacity:1;transform:translateY(0)}}
.result-grid{display:grid;grid-template-columns:repeat(auto-fit,minmax(140px,1fr));gap:12px}
.result-item{text-align:center;padding:16px 12px;background:#fff;border-radius:8px}
.result-item .value{font-size:1.4rem;font-weight:700;color:var(--secondary);word-break:break-all}
.result-item .label{font-size:0.8rem;color:var(--text-light);margin-top:4px}

/* Compliance */
.compliance-box{padding:16px;border-radius:8px;margin-top:16px;font-weight:600;font-size:0.95rem;line-height:1.6}
.compliance-pass{background:#d1fae5;color:#065f46;border:1px solid #a7f3d0}
.compliance-warn{background:#fef3c7;color:#92400e;border:1px solid #fde68a}
.compliance-fail{background:#fee2e2;color:#991b1b;border:1px solid #fecaca}

/* Vehicle DB */
.vehicle-selector{display:grid;grid-template-columns:repeat(3,1fr);gap:12px;margin-bottom:20px}
.vehicle-selector select{width:100%}
.vehicle-info{background:#f8fafc;padding:16px;border-radius:8px;margin-top:12px;border-left:4px solid var(--primary)}

/* Tool Grid */
.tools-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(280px,1fr));gap:20px;margin:30px 0}
.tool-card{background:var(--card);border-radius:var(--radius);padding:24px;box-shadow:var(--shadow);transition:transform .2s,box-shadow .2s;border:1px solid transparent;display:block;color:inherit}
.tool-card:hover{transform:translateY(-4px);box-shadow:0 8px 30px rgba(0,0,0,0.12);border-color:var(--primary)}
.tool-card .icon{width:48px;height:48px;background:linear-gradient(135deg,var(--primary),var(--primary-dark));border-radius:12px;display:flex;align-items:center;justify-content:center;color:#fff;font-size:1.4rem;margin-bottom:16px}
.tool-card h3{font-size:1.1rem;margin-bottom:8px;color:var(--secondary)}
.tool-card p{font-size:0.9rem;color:var(--text-light);margin-bottom:16px}
.tool-card .link{color:var(--primary);font-weight:600;font-size:0.9rem;display:flex;align-items:center;gap:4px}

/* Brand Cards */
.brand-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(260px,1fr));gap:20px}
.brand-card{background:var(--card);border-radius:var(--radius);padding:20px;box-shadow:var(--shadow);border-top:4px solid var(--primary)}
.brand-card h3{font-size:1.1rem;margin-bottom:4px}
.brand-card .company{font-size:0.85rem;color:var(--text-light);margin-bottom:10px}
.brand-card .tags{display:flex;flex-wrap:wrap;gap:6px;margin-bottom:10px}
.brand-card .tag{background:#f1f5f9;padding:4px 10px;border-radius:4px;font-size:0.8rem}
.brand-card .popular{font-size:0.85rem;color:var(--text-light)}

/* Article */
.article-content{max-width:800px;margin:0 auto;background:var(--card);padding:40px;border-radius:var(--radius);box-shadow:var(--shadow)}
.article-content h1{font-size:1.8rem;margin-bottom:20px;color:var(--secondary);line-height:1.3}
.article-content h2{font-size:1.3rem;margin:28px 0 12px;color:var(--secondary);border-bottom:2px solid var(--primary);padding-bottom:6px;display:inline-block}
.article-content h3{font-size:1.1rem;margin:20px 0 10px;color:var(--secondary)}
.article-content p{margin-bottom:16px;color:#334155}
.article-content ul,.article-content ol{margin-bottom:16px;padding-left:24px}
.article-content li{margin-bottom:8px;color:#334155}
.article-content .tip{background:#eff6ff;border-left:4px solid var(--accent);padding:16px;margin:20px 0;border-radius:0 8px 8px 0}
.article-content .warning{background:#fffbeb;border-left:4px solid var(--warning);padding:16px;margin:20px 0;border-radius:0 8px 8px 0}

/* FAQ */
.faq-item{border-bottom:1px solid var(--border);padding:16px 0}
.faq-item:last-child{border-bottom:none}
.faq-item h4{color:var(--secondary);margin-bottom:8px;font-size:1rem}
.faq-item p{color:var(--text-light);font-size:0.95rem}

/* Breadcrumb */
.breadcrumb{display:flex;gap:8px;align-items:center;margin-bottom:20px;font-size:0.9rem;color:var(--text-light);flex-wrap:wrap}
.breadcrumb a{color:var(--accent)}
.breadcrumb span{color:var(--text-light)}

/* Footer */
footer{background:var(--secondary);color:rgba(255,255,255,0.7);padding:40px 0 20px;margin-top:60px}
.footer-grid{display:grid;grid-template-columns:repeat(auto-fit,minmax(200px,1fr));gap:30px;margin-bottom:30px}
.footer-col h4{color:#fff;margin-bottom:16px;font-size:1rem}
.footer-col a{display:block;color:rgba(255,255,255,0.6);margin-bottom:8px;font-size:0.9rem;transition:color .2s}
.footer-col a:hover{color:#fff}
.footer-bottom{text-align:center;padding-top:20px;border-top:1px solid rgba(255,255,255,0.1);font-size:0.85rem}
.footer-bottom a{color:rgba(255,255,255,0.6)}

/* Table */
table{width:100%;border-collapse:collapse;margin:16px 0;font-size:0.9rem;overflow-x:auto;display:block}
th,td{padding:12px;text-align:left;border-bottom:1px solid var(--border);white-space:nowrap}
th{background:#f8fafc;font-weight:600;color:var(--secondary)}
tr:hover{background:#f8fafc}

/* Comparison */
.compare-table{display:grid;grid-template-columns:1fr 1fr;gap:20px;margin-top:20px}
.compare-col{background:#f8fafc;padding:20px;border-radius:10px}
.compare-col h4{margin-bottom:12px;color:var(--secondary)}
.compare-col .spec{display:flex;justify-content:space-between;padding:8px 0;border-bottom:1px solid #e2e8f0;font-size:0.9rem}

/* Schema hidden */
.schema{display:none}

/* Scrollbar */
::-webkit-scrollbar{width:8px}
::-webkit-scrollbar-track{background:#f1f5f9}
::-webkit-scrollbar-thumb{background:#cbd5e1;border-radius:4px}
::-webkit-scrollbar-thumb:hover{background:#94a3b8}

/* Mobile */
@media(max-width:768px){
.hero{padding:40px 16px}
.hero h1{font-size:1.5rem}
.hero p{font-size:1rem}
.nav{display:none;position:absolute;top:64px;left:0;right:0;background:var(--secondary);flex-direction:column;padding:16px;gap:4px;max-height:calc(100vh - 64px);overflow-y:auto}
.nav.active{display:flex}
.mobile-menu-btn{display:block}
.vehicle-selector{grid-template-columns:1fr}
.form-grid{grid-template-columns:1fr}
.tools-grid{grid-template-columns:1fr}
.compare-table{grid-template-columns:1fr}
.article-content{padding:20px}
table{font-size:0.8rem}
th,td{padding:8px}
.card{padding:20px}
.result-item .value{font-size:1.2rem}
}

/* Small mobile */
@media(max-width:400px){
.hero h1{font-size:1.3rem}
.badge{font-size:0.75rem;padding:4px 10px}
.btn{width:100%;justify-content:center}
}

/* Print */
@media print{
header,footer,.nav,.mobile-menu-btn{display:none}
.card{box-shadow:none;border:1px solid #ddd}
}