:root {
    --primary: #2481cc;
    --primary-hover: #1b6ca8;
    --dark: #0f172a;
    --text-main: #334155;
    --text-muted: #64748b;
    --bg-light: #f8fafc;
    --white: #ffffff;
    --border: #e2e8f0;
    --radius: 12px;
}
* { box-sizing: border-box; margin: 0; padding: 0; font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif; }
body { color: var(--text-main); background: var(--white); line-height: 1.6; }
a { text-decoration: none; color: inherit; }
.container { max-width: 1200px; margin: 0 auto; padding: 0 20px; }

/* Header & Footer 共用样式 */
header { background: var(--white); border-bottom: 1px solid var(--border); position: sticky; top: 0; z-index: 1000; }
.nav-wrap { display: flex; justify-content: space-between; align-items: center; height: 72px; }
.logo-area { display: flex; align-items: center; gap: 10px; font-weight: 700; font-size: 20px; color: var(--dark); }
.logo-area img { width: 36px; height: 36px; object-fit: contain; }
nav ul { display: flex; list-style: none; gap: 32px; align-items: center; }
nav ul li a { font-size: 16px; font-weight: 500; color: var(--text-main); transition: color 0.2s; }
nav ul li a:hover, nav ul li a.active { color: var(--primary); }
.header-cta { background: var(--primary); color: var(--white); padding: 10px 20px; border-radius: var(--radius); font-weight: 500; transition: background 0.2s; }
.header-cta:hover { background: var(--primary-hover); }

footer { background: var(--dark); color: #94a3b8; padding: 60px 0 30px; margin-top: 80px; }
.footer-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(200px, 1fr)); gap: 40px; margin-bottom: 40px; }
.footer-col h4 { color: var(--white); margin-bottom: 20px; font-size: 16px; }
.footer-col ul { list-style: none; display: flex; flex-direction: column; gap: 12px; }
.footer-col ul li a:hover { color: var(--white); }
.footer-bottom { border-top: 1px solid #1e293b; padding-top: 20px; text-align: center; font-size: 14px; }

/* 通用排版与内容卡片 */
.hero { padding: 90px 0; text-align: center; background: linear-gradient(180deg, var(--bg-light) 0%, var(--white) 100%); }
.hero h1 { font-size: 42px; color: var(--dark); margin-bottom: 20px; font-weight: 800; letter-spacing: -0.5px; }
.hero p { font-size: 18px; color: var(--text-muted); max-width: 750px; margin: 0 auto 32px; }
.btn-group { display: flex; gap: 16px; justify-content: center; }
.btn-primary { background: var(--primary); color: var(--white); padding: 14px 28px; border-radius: var(--radius); font-weight: 600; font-size: 16px; box-shadow: 0 4px 12px rgba(36,129,204,0.2); }
.btn-secondary { background: var(--bg-light); color: var(--dark); border: 1px solid var(--border); padding: 14px 28px; border-radius: var(--radius); font-weight: 600; font-size: 16px; }

.section { padding: 60px 0; }
.grid-3 { display: grid; grid-template-columns: repeat(auto-fit, minmax(320px, 1fr)); gap: 30px; }
.card { background: var(--bg-light); border: 1px solid var(--border); border-radius: var(--radius); padding: 30px; transition: transform 0.2s; }
.card:hover { transform: translateY(-4px); }
.card h3 { font-size: 20px; color: var(--dark); margin-bottom: 12px; }
.card p { color: var(--text-muted); font-size: 15px; }