:root {
    --primary-color: #2563eb;
    --secondary-color: #1e40af;
    --background-color: #f8fafc;
    --card-background: #ffffff;
    --text-color: #1e293b;
    --border-radius: 8px;
    --transition: all 0.3s ease;
    --shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
    --hover-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
}

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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
    line-height: 1.6;
    color: var(--text-color);
    background-color: var(--background-color);
}

/* Language Switch Styles */
body:lang(en) .zh {
    display: none;
}

body:lang(zh) .en {
    display: none;
}

.lang-switch {
    background: var(--primary-color);
    color: white;
    border: none;
    padding: 0.5rem 1rem;
    border-radius: var(--border-radius);
    cursor: pointer;
    font-weight: bold;
    transition: var(--transition);
    margin-left: 1rem;
}

.lang-switch:hover {
    background: var(--secondary-color);
    transform: translateY(-2px);
}

/* Header Styles */
header {
    background-color: var(--card-background);
    box-shadow: var(--shadow);
    position: sticky;
    top: 0;
    z-index: 1000;
    backdrop-filter: blur(10px);
    background-color: rgba(255, 255, 255, 0.9);
}

nav {
    max-width: 1200px;
    margin: 0 auto;
    padding: 1rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    font-size: 1.5rem;
    font-weight: bold;
    color: var(--primary-color);
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.nav-links {
    display: flex;
    align-items: center;
    gap: 1rem;
}

.nav-links a {
    color: var(--text-color);
    text-decoration: none;
    padding: 0.5rem 1rem;
    border-radius: var(--border-radius);
    transition: var(--transition);
}

.nav-links a:hover {
    color: var(--primary-color);
    background-color: rgba(37, 99, 235, 0.1);
}

.nav-links a.active {
    color: var(--primary-color);
    background-color: rgba(37, 99, 235, 0.1);
}

/* Main Content Styles */
main {
    max-width: 1200px;
    margin: 2rem auto;
    padding: 0 1rem;
}

.section {
    margin-bottom: 3rem;
    animation: fadeIn 0.5s ease-in-out;
}

.section h2 {
    margin-bottom: 1.5rem;
    color: var(--primary-color);
    display: flex;
    align-items: center;
    gap: 0.5rem;
    font-size: 1.8rem;
}

.card-container {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 1.5rem;
}

.card {
    background-color: var(--card-background);
    padding: 1.5rem;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow);
    transition: var(--transition);
    border: 1px solid rgba(0, 0, 0, 0.05);
}

.card:hover {
    transform: translateY(-5px);
    box-shadow: var(--hover-shadow);
}

.card h3 {
    color: var(--primary-color);
    margin-bottom: 1rem;
    font-size: 1.2rem;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.card a {
    display: block;
    color: var(--text-color);
    text-decoration: none;
    padding: 0.5rem 0;
    transition: var(--transition);
    border-bottom: 1px solid transparent;
}

.card a:hover {
    color: var(--primary-color);
    padding-left: 0.5rem;
    border-bottom: 1px solid var(--primary-color);
}

/* Footer Styles */
footer {
    text-align: center;
    padding: 2rem;
    background-color: var(--card-background);
    margin-top: 3rem;
    border-top: 1px solid rgba(0, 0, 0, 0.1);
}

/* Animations */
@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

/* Responsive Design */
@media (max-width: 768px) {
    nav {
        flex-direction: column;
        gap: 1rem;
    }

    .nav-links {
        flex-direction: column;
        width: 100%;
    }

    .nav-links a {
        width: 100%;
        text-align: center;
    }

    .lang-switch {
        margin: 1rem 0 0 0;
        width: 100%;
    }

    .card-container {
        grid-template-columns: 1fr;
    }

    .section h2 {
        font-size: 1.5rem;
    }
}

/* Dark Mode Support */
@media (prefers-color-scheme: dark) {
    :root {
        --background-color: #1a1a1a;
        --card-background: #2d2d2d;
        --text-color: #e5e5e5;
    }

    header {
        background-color: rgba(45, 45, 45, 0.9);
    }

    .card {
        border-color: rgba(255, 255, 255, 0.1);
    }

    footer {
        border-top-color: rgba(255, 255, 255, 0.1);
    }
}