:root {
    --navy: #4a6a8a;
    --navy-light: #6a8aaa;
    --orange: #c9a06e;
    --orange-light: #daba8a;
    --silver: #e2e8f0;
    --gray: #f7f8fa;
    --dark: #1a202c;
    --text: #4a5568;
    --white: #fff;
    --shadow: 0 4px 20px rgba(0,0,0,0.08);
    --radius: 10px;
    --max-w: 1000px;
}

*{margin:0;padding:0;box-sizing:border-box}
body{font-family:-apple-system,"Microsoft YaHei","PingFang SC",sans-serif;background:var(--gray);color:var(--text);line-height:1.6}
a{color:var(--navy);text-decoration:none}

header{background:var(--white);box-shadow:0 2px 12px rgba(0,0,0,0.06);position:sticky;top:0;z-index:100}
header .inner{max-width:var(--max-w);margin:0 auto;padding:0 20px;display:flex;align-items:center;height:64px;gap:24px}
.logo{display:flex;align-items:center;gap:10px;font-size:20px;font-weight:700;color:var(--navy);white-space:nowrap}
.logo .accent{color:var(--orange)}
nav{display:flex;gap:16px;margin-left:auto}
nav a{font-size:14px;color:var(--text);padding:6px 12px;border-radius:6px;transition:.2s;white-space:nowrap}
nav a:hover{color:var(--orange);background:#fff8f0}
nav a.sell{background:var(--orange);color:var(--white);padding:8px 20px;border-radius:20px}
nav a.sell:hover{background:#d35400;color:var(--white)}

.hero{background:linear-gradient(135deg,var(--navy),var(--navy-light) 60%,#8aaaca);color:var(--white);padding:80px 20px 60px;text-align:center}
.hero h1{font-size:32px;margin-bottom:10px;font-weight:700}
.hero .sub{font-size:15px;opacity:.85;max-width:600px;margin:0 auto 28px}
.hero .search-box{max-width:600px;margin:0 auto;background:var(--white);border-radius:50px;display:flex;overflow:hidden;box-shadow:0 4px 20px rgba(0,0,0,0.2)}
.hero .search-box input{flex:1;padding:14px 20px;border:none;font-size:14px;outline:none}
.hero .search-box button{padding:14px 28px;background:var(--orange);color:var(--white);border:none;font-size:14px;font-weight:600;cursor:pointer}
.hero .search-box button:hover{background:#d35400}
.hero-stats{display:flex;justify-content:center;gap:40px;margin-top:32px;flex-wrap:wrap}
.hero-stats .num{font-size:26px;font-weight:700}
.hero-stats .label{font-size:13px;opacity:.75;margin-top:2px}

section{padding:50px 20px}
section .inner{max-width:var(--max-w);margin:0 auto}
.section-title{text-align:center;font-size:22px;font-weight:700;color:var(--navy);margin-bottom:6px}
.section-sub{text-align:center;font-size:14px;color:var(--text);margin-bottom:32px}

/* Quick filters */
.filters{display:flex;gap:10px;flex-wrap:wrap;justify-content:center;margin-bottom:32px}
.filters select{padding:10px 14px;border:1px solid #e0e0e0;border-radius:8px;font-size:13px;background:var(--white);min-width:120px}
.filters .btn{padding:10px 24px;background:var(--navy);color:var(--white);border:none;border-radius:8px;cursor:pointer}

/* Car cards */
.cars{display:grid;grid-template-columns:repeat(3,1fr);gap:16px}
.car-card{background:var(--white);border-radius:var(--radius);overflow:hidden;box-shadow:var(--shadow);transition:.3s}
.car-card:hover{transform:translateY(-4px);box-shadow:0 8px 30px rgba(0,0,0,0.12)}
.car-card .img{height:180px;display:flex;align-items:center;justify-content:center;position:relative}
.car-card .tag{position:absolute;top:10px;left:10px;padding:4px 10px;border-radius:4px;font-size:11px;font-weight:600}
.tag.recommend{background:var(--orange);color:var(--white)}
.tag.new{background:#27ae60;color:var(--white)}
.car-card .info{padding:16px}
.car-card .info h3{font-size:15px;margin-bottom:4px;color:var(--dark)}
.car-card .info .meta{font-size:12px;color:#999;margin-bottom:6px}
.car-card .info .price{font-size:18px;font-weight:700;color:var(--orange)}
.car-card .info .price span{font-size:12px;font-weight:400;color:#999}
.car-card .info .tags{display:flex;gap:4px;flex-wrap:wrap;margin-top:8px}
.car-card .info .tags span{background:var(--silver);padding:2px 8px;border-radius:4px;font-size:11px;color:var(--text)}

/* Features */
.features{display:grid;grid-template-columns:repeat(4,1fr);gap:16px}
.feature-card{background:var(--white);border-radius:var(--radius);padding:28px 20px;text-align:center;box-shadow:var(--shadow)}
.feature-card .icon{width:52px;height:52px;margin:0 auto 12px;border-radius:50%;display:flex;align-items:center;justify-content:center}
.feature-card h3{font-size:14px;margin-bottom:4px;color:var(--dark)}
.feature-card p{font-size:12px;color:#999}

/* Steps */
.steps{display:grid;grid-template-columns:repeat(3,1fr);gap:16px}
.step-card{background:var(--white);border-radius:var(--radius);padding:28px 20px;text-align:center;box-shadow:var(--shadow);position:relative;counter-increment:step}
.step-card .num{width:32px;height:32px;background:var(--navy);color:var(--white);border-radius:50%;display:flex;align-items:center;justify-content:center;margin:0 auto 12px;font-weight:700}
.step-card h3{font-size:14px;margin-bottom:4px;color:var(--dark)}
.step-card p{font-size:12px;color:#999}

/* CTA */
.cta{background:linear-gradient(135deg,var(--navy),var(--navy-light));text-align:center;padding:50px 20px;color:var(--white)}
.cta h2{font-size:22px;margin-bottom:6px}
.cta p{font-size:14px;opacity:.8;margin-bottom:20px}
.cta .btn{display:inline-block;padding:12px 36px;background:var(--orange);color:var(--white);border-radius:24px;font-size:15px;font-weight:600;white-space:nowrap}
.cta .btn:hover{background:#d35400}

/* Sell form */
.form-section{padding:50px 20px}
.form-section .inner{max-width:640px;margin:0 auto;background:var(--white);border-radius:var(--radius);padding:32px;box-shadow:var(--shadow)}
.form-section h2{text-align:center;margin-bottom:24px;color:var(--navy)}
.form-group{margin-bottom:14px}
.form-group label{display:block;font-size:13px;font-weight:600;margin-bottom:4px;color:var(--dark)}
.form-group input,.form-group select,.form-group textarea{width:100%;padding:10px 12px;border:1px solid #e0e0e0;border-radius:8px;font-size:14px}
.form-group input:focus,.form-group select:focus,.form-group textarea:focus{outline:none;border-color:var(--orange);box-shadow:0 0 0 3px rgba(230,126,34,0.1)}
.form-group textarea{min-height:70px;resize:vertical}
.form-row{display:grid;grid-template-columns:1fr 1fr;gap:12px}
.form-submit{width:100%;padding:12px;background:var(--orange);color:var(--white);border:none;border-radius:8px;font-size:15px;font-weight:600;cursor:pointer}
.form-submit:hover{background:#d35400}
.form-tip{text-align:center;font-size:12px;color:#999;margin-top:10px}

/* Footer */
footer{background:var(--dark);color:rgba(255,255,255,0.6);padding:36px 20px 16px}
footer .inner{max-width:var(--max-w);margin:0 auto;display:grid;grid-template-columns:2fr 1fr 1fr 1fr;gap:24px}
footer h4{color:var(--white);font-size:13px;margin-bottom:10px}
footer p,footer a{font-size:12px;line-height:2;color:rgba(255,255,255,0.5)}
footer a:hover{color:var(--orange)}
footer .bottom{border-top:1px solid rgba(255,255,255,0.08);margin-top:24px;padding-top:14px;text-align:center;font-size:11px}

/* Back to top */
.btt{position:fixed;bottom:30px;right:30px;width:44px;height:44px;background:var(--orange);color:var(--white);border:none;border-radius:50%;font-size:20px;cursor:pointer;box-shadow:0 2px 12px rgba(0,0,0,0.2);display:none;z-index:99}

/* About */
.about-content{background:var(--white);border-radius:var(--radius);padding:32px;box-shadow:var(--shadow);line-height:2;font-size:14px}

/* Mobile */
@media(max-width:768px){
    .cta .btn{width:100%;max-width:70vw;font-size:13px;padding:10px 18px;overflow:hidden;text-overflow:ellipsis;white-space:nowrap}
    a[style*="inline-block"]{overflow:hidden;text-overflow:ellipsis;white-space:nowrap;max-width:70vw!important}
    header .inner{height:auto;min-height:56px;padding:0 12px;gap:8px;flex-wrap:wrap}
    .logo{font-size:17px}
    .logo svg{width:80px;height:28px}
    nav{gap:4px;margin-left:auto;overflow-x:auto;white-space:nowrap;-webkit-overflow-scrolling:touch;scrollbar-width:none;padding:8px 0}
    nav::-webkit-scrollbar{display:none}
    nav a{font-size:11px;padding:4px 5px;overflow:hidden;text-overflow:ellipsis;max-width:30vw}
    nav a.sell{padding:5px 10px;font-size:11px}
    .cars{grid-template-columns:1fr}
    .features{grid-template-columns:repeat(2,1fr)}
    .steps{grid-template-columns:1fr}
    footer .inner{grid-template-columns:1fr 1fr}
    footer .inner div:first-child{grid-column:1/-1}
    .hero{padding:50px 16px 36px}
    .hero h1{font-size:22px}
    .hero .sub{font-size:13px}
    .hero .search-box{flex-direction:column;border-radius:12px}
    .hero .search-box button{padding:12px 20px;width:100%}
    .hero-stats{gap:16px}
    .hero-stats .num{font-size:20px}
    nav a[href*="value"]{display:none}
    .form-row{grid-template-columns:1fr}
    .form-section .inner{padding:20px}
    section{padding:36px 14px}
    .section-title{font-size:18px}
    .section-sub{margin-bottom:24px}
    .cta{padding:36px 16px}
    .cta h2{font-size:18px}
}