:root {
    /* Clean Light Theme */
    --bg-white: #ffffff;
    --bg-light: #f8fafc;
    --bg-muted: #f1f5f9;
    
    --text-dark: #0f172a;
    --text-body: #334155;
    --text-muted: #64748b;
    --text-light: #94a3b8;
    
    --border-light: #e2e8f0;
    --border-muted: #cbd5e1;
    
    /* Brand Colors */
    --brand-primary: #dc2626;
    --brand-hover: #b91c1c;
    --brand-bg: #fef2f2;
    --brand-border: #fecaca;
    
    --accent-blue: #3b82f6;
    
    --radius: 12px;
    --radius-sm: 8px;
    --radius-lg: 16px;
    
    --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.05);
    --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.1), 0 2px 4px -2px rgb(0 0 0 / 0.1);
    --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.1), 0 4px 6px -4px rgb(0 0 0 / 0.1);
    
    --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", "Noto Sans SC", "PingFang SC", "Microsoft YaHei", sans-serif;
}

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

html {
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-sans);
    line-height: 1.6;
    color: var(--text-body);
    background-color: var(--bg-white);
    -webkit-font-smoothing: antialiased;
}

a {
    text-decoration: none;
    color: inherit;
    transition: color 0.2s ease;
}

ul {
    list-style: none;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 24px;
}

/* ========== Header ========== */
.site-header {
    background: var(--bg-white);
    border-bottom: 1px solid var(--border-light);
    position: sticky;
    top: 0;
    z-index: 100;
    padding: 16px 0;
}

.site-header .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo-container {
    display: flex;
    align-items: center;
    gap: 10px;
}

.site-logo {
    height: 32px;
    width: 32px;
    border-radius: var(--radius-sm);
    object-fit: cover;
}

.site-title {
    font-size: 18px;
    font-weight: 700;
    color: var(--text-dark);
}

.site-nav ul {
    display: flex;
    gap: 32px;
    align-items: center;
}

.site-nav a {
    font-size: 15px;
    font-weight: 500;
    color: var(--text-muted);
}

.site-nav a:hover {
    color: var(--text-dark);
}

.btn-nav {
    background: var(--brand-primary);
    color: white !important;
    padding: 10px 20px;
    border-radius: var(--radius-sm);
    font-weight: 600;
    font-size: 14px !important;
}

.btn-nav:hover {
    background: var(--brand-hover);
}

/* ========== Hero Section ========== */
.hero-section {
    padding: 100px 0 80px;
    text-align: center;
    background: linear-gradient(180deg, var(--bg-light) 0%, var(--bg-white) 100%);
    border-bottom: 1px solid var(--border-light);
}

.hero-section h1 {
    font-size: 48px;
    font-weight: 800;
    color: var(--text-dark);
    line-height: 1.2;
    margin-bottom: 20px;
    letter-spacing: -0.02em;
}

.hero-subtitle {
    font-size: 20px;
    color: var(--text-muted);
    margin-bottom: 40px;
    max-width: 600px;
    margin-left: auto;
    margin-right: auto;
}

.hero-buttons {
    display: flex;
    justify-content: center;
    gap: 16px;
    flex-wrap: wrap;
}

.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 14px 28px;
    border-radius: var(--radius-sm);
    font-weight: 600;
    font-size: 16px;
    cursor: pointer;
    transition: all 0.2s ease;
    border: none;
}

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

.btn-primary:hover {
    background: var(--brand-hover);
    transform: translateY(-1px);
    box-shadow: var(--shadow-md);
}

.btn-outline {
    background: var(--bg-white);
    color: var(--text-dark);
    border: 1px solid var(--border-muted);
}

.btn-outline:hover {
    background: var(--bg-light);
    border-color: var(--text-muted);
}

/* ========== Section Common ========== */
.section-label {
    display: inline-block;
    font-size: 13px;
    font-weight: 600;
    color: var(--brand-primary);
    background: var(--brand-bg);
    padding: 6px 14px;
    border-radius: 20px;
    margin-bottom: 16px;
    border: 1px solid var(--brand-border);
}

.section-title {
    text-align: center;
    font-size: 36px;
    margin-bottom: 16px;
    font-weight: 700;
    color: var(--text-dark);
    letter-spacing: -0.02em;
}

.section-desc {
    text-align: center;
    font-size: 18px;
    color: var(--text-muted);
    max-width: 700px;
    margin: 0 auto 60px;
}

/* ========== Features Section ========== */
.features-section {
    padding: 100px 0;
    background: var(--bg-white);
}

.features-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 24px;
}

.feature-card {
    padding: 32px;
    border-radius: var(--radius-lg);
    background: var(--bg-white);
    border: 1px solid var(--border-light);
    transition: all 0.3s ease;
}

.feature-card:hover {
    border-color: var(--border-muted);
    box-shadow: var(--shadow-lg);
    transform: translateY(-4px);
}

.feature-card h3 {
    font-size: 20px;
    margin-bottom: 12px;
    color: var(--text-dark);
    font-weight: 600;
}

.feature-card p {
    color: var(--text-body);
    font-size: 15px;
    line-height: 1.7;
}

/* ========== Content Section ========== */
.content-section {
    padding: 100px 0;
    background: var(--bg-light);
    border-top: 1px solid var(--border-light);
    border-bottom: 1px solid var(--border-light);
}

.article-content {
    max-width: 800px;
    margin: 0 auto;
    background: var(--bg-white);
    padding: 48px;
    border-radius: var(--radius-lg);
    border: 1px solid var(--border-light);
    box-shadow: var(--shadow-sm);
}

.article-content h2 {
    font-size: 28px;
    margin-bottom: 24px;
    color: var(--text-dark);
    font-weight: 700;
    padding-bottom: 16px;
    border-bottom: 1px solid var(--border-light);
}

.article-content h3 {
    font-size: 22px;
    margin-top: 40px;
    margin-bottom: 16px;
    color: var(--text-dark);
    font-weight: 600;
}

.article-content h4 {
    font-size: 18px;
    margin-top: 28px;
    margin-bottom: 12px;
    color: var(--text-dark);
    font-weight: 600;
}

.article-content p {
    margin-bottom: 16px;
    color: var(--text-body);
    font-size: 16px;
    line-height: 1.8;
}

.article-content strong {
    color: var(--text-dark);
    font-weight: 600;
}

.article-content ul {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 16px;
    margin: 24px 0;
}

.article-content li {
    padding: 20px;
    background: var(--bg-light);
    border: 1px solid var(--border-light);
    border-radius: var(--radius);
    font-size: 15px;
    color: var(--text-body);
    line-height: 1.6;
}

.article-content li strong {
    display: block;
    margin-bottom: 4px;
    color: var(--text-dark);
}

/* ========== Download Section ========== */
.download-section {
    padding: 100px 0;
    text-align: center;
    background: var(--bg-white);
}

.download-section h2 {
    font-size: 36px;
    margin-bottom: 12px;
    color: var(--text-dark);
    font-weight: 700;
}

.download-section > .container > p {
    color: var(--text-muted);
    margin-bottom: 48px;
    font-size: 18px;
}

.download-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
    gap: 24px;
    max-width: 900px;
    margin: 0 auto 40px;
}

.download-card {
    padding: 40px 28px;
    border-radius: var(--radius-lg);
    background: var(--bg-white);
    border: 1px solid var(--border-light);
    transition: all 0.3s ease;
}

.download-card:hover {
    border-color: var(--brand-primary);
    box-shadow: var(--shadow-lg);
    transform: translateY(-4px);
}

.os-icon {
    font-size: 40px;
    margin-bottom: 16px;
    display: block;
}

.download-card h3 {
    font-size: 20px;
    margin-bottom: 8px;
    color: var(--text-dark);
    font-weight: 600;
}

.download-card p {
    color: var(--text-muted);
    margin-bottom: 24px;
    font-size: 14px;
}

.btn-download {
    display: block;
    width: 100%;
    padding: 12px 0;
    background: var(--brand-primary);
    color: white;
    border-radius: var(--radius-sm);
    font-weight: 600;
    font-size: 14px;
    transition: all 0.2s ease;
}

.btn-download:hover {
    background: var(--brand-hover);
}

.version-info {
    font-size: 14px;
    color: var(--text-light);
}

/* ========== Footer ========== */
.site-footer {
    background: var(--bg-light);
    padding: 60px 0 40px;
    border-top: 1px solid var(--border-light);
}

.footer-content {
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 24px;
    margin-bottom: 32px;
}

.footer-logo {
    display: flex;
    align-items: center;
    gap: 10px;
    font-weight: 600;
    font-size: 16px;
    color: var(--text-dark);
}

.footer-logo img {
    height: 28px;
    border-radius: var(--radius-sm);
}

.footer-links {
    display: flex;
    gap: 24px;
}

.footer-links a {
    color: var(--text-muted);
    font-size: 14px;
    font-weight: 500;
}

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

.copyright {
    text-align: center;
    color: var(--text-light);
    font-size: 13px;
    padding-top: 32px;
    border-top: 1px solid var(--border-light);
}

/* ========== Responsive ========== */
@media (max-width: 768px) {
    .hero-section {
        padding: 80px 0 60px;
    }
    
    .hero-section h1 {
        font-size: 32px;
    }

    .hero-subtitle {
        font-size: 16px;
    }
    
    .hero-buttons {
        flex-direction: column;
        padding: 0 20px;
    }
    
    .btn {
        width: 100%;
    }

    .site-header .container {
        flex-direction: column;
        gap: 16px;
    }

    .site-nav ul {
        flex-wrap: wrap;
        justify-content: center;
        gap: 16px;
    }
    
    .section-title {
        font-size: 28px;
    }
    
    .article-content {
        padding: 24px;
    }
    
    .article-content ul {
        grid-template-columns: 1fr;
    }
    
    .footer-content {
        flex-direction: column;
        text-align: center;
    }
    
    .footer-links {
        justify-content: center;
    }
}