:root {
    --primary-color: #2563eb;
    --primary-dark: #1d4ed8;
    --secondary-color: #f1f5f9;
    --text-color: #1e293b;
    --text-light: #64748b;
    --bg-color: #ffffff;
    --accent-color: #38bdf8;
    --border-color: #e2e8f0;
    --font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
    --transition: all 0.3s ease;
}

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

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

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

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

ul {
    list-style: none;
}

/* Header & Nav */
header {
    background-color: var(--bg-color);
    box-shadow: 0 1px 3px rgba(0,0,0,0.05);
    position: fixed;
    width: 100%;
    top: 0;
    z-index: 1000;
}

nav {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1.2rem 5%;
    max-width: 1400px;
    margin: 0 auto;
}

.logo {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--primary-color);
    letter-spacing: -0.5px;
}

.nav-links {
    display: flex;
    gap: 2rem;
    align-items: center;
}

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

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

.lang-toggle {
    background-color: var(--secondary-color);
    border: none;
    padding: 0.5rem 1rem;
    border-radius: 4px;
    cursor: pointer;
    font-weight: 600;
    color: var(--text-color);
    transition: var(--transition);
}

.lang-toggle:hover {
    background-color: #e2e8f0;
}

/* Sections */
section {
    padding: 5rem 5%;
    max-width: 1400px;
    margin: 0 auto;
}

.section-title {
    font-size: 2.5rem;
    font-weight: 700;
    margin-bottom: 3rem;
    text-align: center;
    color: var(--text-color);
}

/* Hero Section */
.hero {
    margin-top: 5rem;
    padding: 8rem 5%;
    background-color: var(--secondary-color);
    text-align: center;
    max-width: 100%;
}

.hero h1 {
    font-size: 3.5rem;
    font-weight: 800;
    margin-bottom: 1.5rem;
    color: var(--text-color);
    line-height: 1.2;
}

.hero p {
    font-size: 1.25rem;
    color: var(--text-light);
    max-width: 800px;
    margin: 0 auto 2.5rem;
}

.btn {
    display: inline-block;
    padding: 1rem 2.5rem;
    background-color: var(--primary-color);
    color: white;
    font-weight: 600;
    border-radius: 4px;
    transition: var(--transition);
    border: none;
    cursor: pointer;
}

.btn:hover {
    background-color: var(--primary-dark);
    color: white;
    transform: translateY(-2px);
}

/* Services Grid */
.services-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 2rem;
}

.service-card {
    background: var(--bg-color);
    padding: 2.5rem;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    transition: var(--transition);
}

.service-card:hover {
    box-shadow: 0 10px 30px rgba(0,0,0,0.05);
    border-color: var(--primary-color);
    transform: translateY(-5px);
}

.service-icon {
    font-size: 2.5rem;
    color: var(--primary-color);
    margin-bottom: 1.5rem;
}

.service-card h3 {
    font-size: 1.5rem;
    margin-bottom: 1rem;
}

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

/* Content Pages (Privacy, Terms) */
.page-header {
    background-color: var(--primary-color);
    color: white;
    padding: 8rem 5% 4rem;
    text-align: center;
    max-width: 100%;
}

.page-header h1 {
    font-size: 3rem;
    margin-bottom: 1rem;
    color: white;
}

.page-content {
    max-width: 900px;
    margin: 0 auto;
    padding: 4rem 5%;
}

.page-content h2 {
    font-size: 2rem;
    margin: 2.5rem 0 1rem;
    color: var(--text-color);
}

.page-content h3 {
    font-size: 1.5rem;
    margin: 1.5rem 0 0.5rem;
}

.page-content p {
    margin-bottom: 1.5rem;
    color: var(--text-light);
}

.page-content ul {
    list-style: disc;
    margin-left: 2rem;
    margin-bottom: 1.5rem;
    color: var(--text-light);
}

.page-content li {
    margin-bottom: 0.5rem;
}

.contact-info-box {
    background-color: var(--secondary-color);
    padding: 2rem;
    border-radius: 8px;
    margin-top: 2rem;
    border-left: 4px solid var(--primary-color);
}

.contact-info-box p {
    margin-bottom: 0.5rem;
    color: var(--text-color);
}

/* Footer */
footer {
    background-color: var(--text-color);
    color: white;
    padding: 4rem 5% 2rem;
    margin-top: 4rem;
}

.footer-content {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 3rem;
    max-width: 1400px;
    margin: 0 auto 3rem;
}

.footer-col h4 {
    font-size: 1.25rem;
    margin-bottom: 1.5rem;
    color: white;
}

.footer-col p, .footer-col a {
    color: #cbd5e1;
    margin-bottom: 0.75rem;
    display: block;
}

.footer-col a:hover {
    color: var(--accent-color);
}

.footer-bottom {
    text-align: center;
    padding-top: 2rem;
    border-top: 1px solid #334155;
    color: #94a3b8;
}

/* Language Switch Classes */
.lang-zh {
    display: none;
}

/* Responsive */
@media (max-width: 768px) {
    .nav-links {
        display: none; /* In a real app, add a hamburger menu */
    }
    
    .hero h1 {
        font-size: 2.5rem;
    }
    
    .section-title {
        font-size: 2rem;
    }
}