:root {
    --primary-color: #2563eb;
    --primary-dark: #1d4ed8;
    --secondary-color: #0f172a;
    --text-main: #334155;
    --text-muted: #64748b;
    --bg-main: #f8fafc;
    --bg-white: #ffffff;
    --border-color: #e2e8f0;
    --footer-bg: #0f172a;
    --footer-text: #cbd5e1;
    --font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: var(--font-family);
    color: var(--text-main);
    background-color: var(--bg-main);
    line-height: 1.6;
    overflow-x: hidden;
}

body.lang-en .lang-zh {
    display: none !important;
}

body.lang-zh .lang-en {
    display: none !important;
}

a {
    text-decoration: none;
    color: var(--primary-color);
    transition: color 0.3s ease;
}

a:hover {
    color: var(--primary-dark);
}

ul {
    list-style: none;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
}

/* Header */
header {
    background-color: var(--bg-white);
    box-shadow: 0 2px 4px rgba(0,0,0,0.05);
    position: sticky;
    top: 0;
    z-index: 1000;
}

.navbar {
    display: flex;
    justify-content: space-between;
    align-items: center;
    height: 80px;
}

.logo {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--secondary-color);
    display: flex;
    align-items: center;
    gap: 10px;
}

.nav-links {
    display: flex;
    gap: 30px;
    align-items: center;
}

.nav-links a {
    color: var(--text-main);
    font-weight: 500;
}

.nav-links a:hover {
    color: var(--primary-color);
}

.lang-switch {
    background: transparent;
    border: 1px solid var(--border-color);
    padding: 6px 12px;
    border-radius: 4px;
    cursor: pointer;
    font-size: 0.9rem;
    font-family: inherit;
    color: var(--text-main);
    transition: all 0.3s ease;
}

.lang-switch:hover {
    border-color: var(--primary-color);
    color: var(--primary-color);
}

/* Hero Section */
.hero {
    background: linear-gradient(135deg, var(--secondary-color) 0%, var(--primary-dark) 100%);
    color: white;
    padding: 100px 0;
    text-align: center;
}

.hero h1 {
    font-size: 3.5rem;
    margin-bottom: 20px;
    font-weight: 800;
    letter-spacing: -1px;
}

.hero p {
    font-size: 1.25rem;
    max-width: 800px;
    margin: 0 auto 40px;
    opacity: 0.9;
}

.btn {
    display: inline-block;
    padding: 12px 30px;
    border-radius: 6px;
    font-weight: 600;
    font-size: 1.1rem;
    transition: all 0.3s ease;
    border: none;
    cursor: pointer;
}

.btn-primary {
    background-color: var(--primary-color);
    color: white;
}

.btn-primary:hover {
    background-color: #1e40af;
    color: white;
}

.btn-light {
    background-color: white;
    color: var(--secondary-color);
}

.btn-light:hover {
    background-color: #f8fafc;
    color: var(--primary-color);
}

/* Sections */
.section {
    padding: 80px 0;
}

.section-bg {
    background-color: var(--bg-white);
}

.section-title {
    text-align: center;
    font-size: 2.5rem;
    color: var(--secondary-color);
    margin-bottom: 50px;
}

.section-title::after {
    content: '';
    display: block;
    width: 60px;
    height: 4px;
    background-color: var(--primary-color);
    margin: 15px auto 0;
    border-radius: 2px;
}

/* Cards Grid */
.grid-3 {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 30px;
}

.card {
    background: var(--bg-white);
    padding: 40px;
    border-radius: 8px;
    box-shadow: 0 4px 6px rgba(0,0,0,0.05);
    transition: transform 0.3s ease, box-shadow 0.3s ease;
    border: 1px solid var(--border-color);
}

.card:hover {
    transform: translateY(-5px);
    box-shadow: 0 10px 15px rgba(0,0,0,0.1);
}

.card-icon {
    font-size: 2.5rem;
    color: var(--primary-color);
    margin-bottom: 20px;
}

.card h3 {
    font-size: 1.5rem;
    color: var(--secondary-color);
    margin-bottom: 15px;
}

.card p {
    color: var(--text-muted);
}

/* Content Pages (Privacy, Terms, Services) */
.page-header {
    background-color: var(--secondary-color);
    color: white;
    padding: 60px 0;
    text-align: center;
}

.page-header h1 {
    font-size: 2.5rem;
}

.content-box {
    background: var(--bg-white);
    padding: 50px;
    border-radius: 8px;
    box-shadow: 0 2px 10px rgba(0,0,0,0.05);
    margin-top: -30px;
    margin-bottom: 60px;
    position: relative;
    border: 1px solid var(--border-color);
}

.content-box h2 {
    color: var(--secondary-color);
    margin: 30px 0 15px;
    font-size: 1.8rem;
}

.content-box h3 {
    color: var(--secondary-color);
    margin: 25px 0 10px;
    font-size: 1.4rem;
}

.content-box p {
    margin-bottom: 15px;
    color: var(--text-main);
}

.content-box ul {
    margin-bottom: 20px;
    padding-left: 20px;
    list-style-type: disc;
}

.content-box li {
    margin-bottom: 8px;
    color: var(--text-main);
}

/* Footer */
footer {
    background-color: var(--footer-bg);
    color: var(--footer-text);
    padding: 60px 0 30px;
}

.footer-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 40px;
    margin-bottom: 40px;
}

.footer-col h4 {
    color: white;
    font-size: 1.2rem;
    margin-bottom: 20px;
}

.footer-col p {
    margin-bottom: 10px;
}

.footer-links li {
    margin-bottom: 10px;
}

.footer-links a {
    color: var(--footer-text);
}

.footer-links a:hover {
    color: white;
}

.footer-bottom {
    text-align: center;
    padding-top: 30px;
    border-top: 1px solid rgba(255,255,255,0.1);
    font-size: 0.9rem;
}

@media (max-width: 768px) {
    .nav-links {
        display: none;
    }
    .hero h1 {
        font-size: 2.5rem;
    }
    .content-box {
        padding: 30px;
    }
}