/* CSS Variables for theming */
:root {
    /* Light mode colors */
    --primary-color: #007BFF;
    --primary-hover: #0056b3;
    --bg-color: #ffffff;
    --bg-gradient-start: #f8fbff;
    --bg-gradient-end: #e8f4ff;
    --card-bg: #ffffff;
    --card-shadow: rgba(0, 123, 255, 0.1);
    --text-primary: #333333;
    --text-secondary: #666666;
    --text-tertiary: #999999;
    --border-color: rgba(0, 123, 255, 0.2);
    --wave-color: rgba(0, 123, 255, 0.1);
    --icon-color: #007BFF;
    
    /* Spacing */
    --spacing-xs: 8px;
    --spacing-sm: 16px;
    --spacing-md: 24px;
    --spacing-lg: 32px;
    --spacing-xl: 48px;
    
    /* Typography */
    --font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    --font-size-xs: 12px;
    --font-size-sm: 14px;
    --font-size-md: 16px;
    --font-size-lg: 20px;
    --font-size-xl: 28px;
    --font-size-xxl: 48px;
    
    /* Border radius */
    --radius-sm: 8px;
    --radius-md: 12px;
    --radius-lg: 16px;
    
    /* Transitions */
    --transition-fast: 0.2s ease;
    --transition-normal: 0.3s ease;
}

/* Dark mode */
@media (prefers-color-scheme: dark) {
    :root {
        --primary-color: #4da3ff;
        --primary-hover: #007BFF;
        --bg-color: #0a0a0a;
        --bg-gradient-start: #0f0f0f;
        --bg-gradient-end: #1a1a2e;
        --card-bg: #1a1a1a;
        --card-shadow: rgba(77, 163, 255, 0.15);
        --text-primary: #ffffff;
        --text-secondary: #cccccc;
        --text-tertiary: #888888;
        --border-color: rgba(77, 163, 255, 0.3);
        --wave-color: rgba(77, 163, 255, 0.2);
        --icon-color: #4da3ff;
    }
}

/* Reset and base styles */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    font-size: 16px;
}

body {
    font-family: var(--font-family);
    background: linear-gradient(180deg, var(--bg-gradient-start) 0%, var(--bg-gradient-end) 100%);
    color: var(--text-primary);
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    position: relative;
    overflow-x: hidden;
}

/* Background wave effect */
.background-wave {
    position: fixed;
    bottom: 0;
    left: 0;
    right: 0;
    height: 400px;
    background: linear-gradient(180deg, transparent 0%, var(--wave-color) 100%);
    pointer-events: none;
    z-index: 0;
}

.background-wave::before {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    right: 0;
    height: 200px;
    background: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 1440 320'%3E%3Cpath fill='%23007BFF' fill-opacity='0.1' d='M0,160L48,144C96,128,192,96,288,106.7C384,117,480,171,576,186.7C672,203,768,181,864,154.7C960,128,1056,96,1152,90.7C1248,85,1344,107,1392,117.3L1440,128L1440,320L1392,320C1344,320,1248,320,1152,320C1056,320,960,320,864,320C768,320,672,320,576,320C480,320,384,320,288,320C192,320,96,320,48,320L0,320Z'%3E%3C/path%3E%3C/svg%3E") no-repeat bottom;
    background-size: cover;
    opacity: 0.5;
}

/* Header styles */
.header {
    position: relative;
    z-index: 10;
    padding: var(--spacing-md) var(--spacing-lg);
    display: flex;
    justify-content: center;
}

.header-content {
    width: 100%;
    max-width: 1200px;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
}

.site-title {
    font-size: var(--font-size-lg);
    font-weight: 600;
    color: var(--text-primary);
    letter-spacing: -0.5px;
}

.header-right {
    display: flex;
    align-items: center;
}

.cloudflare-icon {
    width: 32px;
    height: 32px;
    color: var(--icon-color);
    transition: transform var(--transition-normal);
}

.header-right:hover .cloudflare-icon {
    transform: scale(1.1);
}

/* Main content styles */
.main-content {
    flex: 1;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    padding: var(--spacing-xl) var(--spacing-lg);
    position: relative;
    z-index: 1;
}

.hero {
    text-align: center;
    margin-bottom: var(--spacing-xl);
}

.main-title {
    font-size: clamp(32px, 8vw, var(--font-size-xxl));
    font-weight: 700;
    color: var(--primary-color);
    letter-spacing: -2px;
    margin-bottom: var(--spacing-sm);
    text-shadow: 0 2px 10px var(--card-shadow);
}

.subtitle {
    font-size: var(--font-size-md);
    color: var(--text-secondary);
    font-weight: 400;
    letter-spacing: 2px;
}

/* Cards container */
.cards-container {
    display: grid;
    grid-template-columns: 1fr;
    gap: var(--spacing-md);
    width: 100%;
    max-width: 900px;
}

/* Card styles */
.card {
    display: block;
    background: var(--card-bg);
    border-radius: var(--radius-lg);
    padding: var(--spacing-lg);
    text-decoration: none;
    color: inherit;
    box-shadow: 0 4px 20px var(--card-shadow);
    border: 1px solid var(--border-color);
    transition: all var(--transition-normal);
    position: relative;
    overflow: hidden;
}

.card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 3px;
    background: linear-gradient(90deg, var(--primary-color), transparent);
    opacity: 0;
    transition: opacity var(--transition-normal);
}

.card:hover::before {
    opacity: 1;
}

.card:hover {
    transform: translateY(-4px);
    box-shadow: 0 8px 30px var(--card-shadow);
}

.card.disabled {
    cursor: not-allowed;
    opacity: 0.7;
}

.card.disabled:hover {
    transform: none;
    box-shadow: 0 4px 20px var(--card-shadow);
}

.card-content {
    position: relative;
    z-index: 1;
}

.card-title {
    font-size: var(--font-size-xl);
    font-weight: 600;
    color: var(--primary-color);
    margin-bottom: var(--spacing-xs);
}

.card-description {
    font-size: var(--font-size-sm);
    color: var(--text-tertiary);
    line-height: 1.6;
}

/* Footer styles */
.footer {
    position: relative;
    z-index: 10;
    padding: var(--spacing-xl) var(--spacing-lg);
    text-align: center;
}

.footer-content {
    max-width: 1200px;
    margin: 0 auto;
}

.social-links {
    margin-bottom: var(--spacing-md);
}

.social-weibo,
.social-twitter {
    font-size: var(--font-size-md);
    color: var(--text-secondary);
    margin: var(--spacing-xs) 0;
    font-weight: 500;
}

.copyright {
    font-size: var(--font-size-xs);
    color: var(--text-tertiary);
    margin-top: var(--spacing-md);
}

/* Desktop styles */
@media (min-width: 768px) {
    .header {
        padding: var(--spacing-lg) var(--spacing-xl);
    }
    
    .site-title {
        font-size: var(--font-size-xl);
    }
    
    .main-content {
        padding: var(--spacing-xl) var(--spacing-xl);
    }
    
    .hero {
        margin-bottom: var(--spacing-xl);
    }
    
    .subtitle {
        font-size: var(--font-size-lg);
    }
    
    .cards-container {
        grid-template-columns: repeat(3, 1fr);
        gap: var(--spacing-lg);
    }
    
    .card {
        padding: var(--spacing-xl);
    }
    
    .card-title {
        font-size: var(--font-size-xl);
    }
    
    .card-description {
        font-size: var(--font-size-md);
    }
    
    .footer {
        padding: var(--spacing-xl);
    }
    
    .social-links {
        display: flex;
        justify-content: center;
        gap: var(--spacing-lg);
    }
    
    .social-weibo,
    .social-twitter {
        font-size: var(--font-size-lg);
    }
}

/* Mobile optimization */
@media (max-width: 767px) {
    .header {
        padding: var(--spacing-sm) var(--spacing-md);
    }
    

    .site-title {
        font-size: var(--font-size-md);
    }
    
    .cloudflare-icon {
        width: 28px;
        height: 28px;
    }
    
    .main-content {
        padding: var(--spacing-lg) var(--spacing-md);
    }
    
    .main-title {
        letter-spacing: -1px;
    }
    
    .subtitle {
        font-size: var(--font-size-sm);
        letter-spacing: 1px;
    }
    
    .cards-container {
        gap: var(--spacing-sm);
    }
    
    .card {
        padding: var(--spacing-md);
    }
    
    .card-title {
        font-size: var(--font-size-lg);
    }
    
    .card-description {
        font-size: var(--font-size-xs);
    }
    
    .footer {
        padding: var(--spacing-lg) var(--spacing-md);
    }
    
    .social-weibo,
    .social-twitter {
        font-size: var(--font-size-sm);
    }
    
    .copyright {
        font-size: 10px;
    }
}

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

.card {
    animation: fadeInUp 0.5s ease forwards;
}

.card:nth-child(1) {
    animation-delay: 0.1s;
}

.card:nth-child(2) {
    animation-delay: 0.2s;
}

.card:nth-child(3) {
    animation-delay: 0.3s;
}

/* Accessibility improvements */
@media (prefers-reduced-motion: reduce) {
    * {
        animation: none !important;
        transition: none !important;
    }
}

/* Focus styles for accessibility */
.card:focus {
    outline: 2px solid var(--primary-color);
    outline-offset: 2px;
}

/* Print styles */
@media print {
    .background-wave,
    .header {
        display: none;
    }
    
    body {
        background: white;
        color: black;
    }
    
    .card {
        border: 1px solid #ccc;
        box-shadow: none;
    }
}