/* 重置样式和基础设置 */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

:root {
    --primary: #4285f4;
    --primary-dark: #3367d6;
    --secondary: #34a853;
    --accent: #ea4335;
    --warning: #fbbc04;
    --text: #202124;
    --text-light: #5f6368;
    --text-muted: #9aa0a6;
    --background: #ffffff;
    --surface: #f8f9fa;
    --border: #dadce0;
    --shadow: 0 2px 8px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 4px 16px rgba(0, 0, 0, 0.15);
    --shadow-xl: 0 8px 24px rgba(0, 0, 0, 0.2);
}

body {
    font-family: 'Google Sans', 'Segoe UI', -apple-system, BlinkMacSystemFont, 'Roboto', sans-serif;
    line-height: 1.6;
    color: var(--text);
    background: var(--background);
    min-height: 100vh;
    transition: opacity 0.3s ease;
    opacity: 1;
}

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

/* 导航栏 */
.navbar {
    background: var(--background);
    border-bottom: 1px solid var(--border);
    padding: 16px 0;
    position: sticky;
    top: 0;
    z-index: 1000;
    backdrop-filter: blur(10px);
    box-shadow: var(--shadow);
}

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

.logo {
    font-size: 1.5rem;
    font-weight: 600;
    color: var(--text);
    text-decoration: none;
}

.logo span {
    color: var(--primary);
}

.nav-menu {
    display: flex;
    list-style: none;
    gap: 32px;
}

.nav-menu a {
    color: var(--text-light);
    text-decoration: none;
    font-weight: 500;
    transition: all 0.3s ease;
    padding: 8px 16px;
    border-radius: 4px;
}

.nav-menu a:hover,
.nav-menu a.active {
    color: var(--primary);
    background: rgba(66, 133, 244, 0.1);
}

.download-link {
    color: var(--primary) !important;
    font-weight: 600 !important;
}

/* 按钮样式 */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    padding: 12px 32px;
    border-radius: 8px;
    text-decoration: none;
    font-weight: 500;
    font-size: 1rem;
    transition: all 0.3s ease;
    border: none;
    cursor: pointer;
}

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

.btn-primary:hover {
    background: var(--primary-dark);
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
}

.btn-secondary {
    background: var(--surface);
    color: var(--text);
    border: 1px solid var(--border);
}

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

.btn-outline {
    background: transparent;
    color: var(--text-light);
    border: 1px solid var(--border);
}

.btn-outline:hover {
    border-color: var(--primary);
    color: var(--primary);
}

.btn-large {
    padding: 16px 48px;
    font-size: 1.1rem;
}

.btn-download {
    width: 100%;
    margin-top: 16px;
}

/* 英雄区域 */
.hero {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    text-align: center;
    padding: 80px 0;
    margin-bottom: 48px;
}

.hero-title {
    font-size: 3.5rem;
    font-weight: 600;
    margin-bottom: 16px;
    text-shadow: 0 2px 4px rgba(0, 0, 0, 0.2);
}

.hero-subtitle {
    font-size: 1.8rem;
    margin-bottom: 12px;
    opacity: 0.95;
}

.hero-tagline {
    font-size: 1.2rem;
    margin-bottom: 40px;
    opacity: 0.9;
}

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

/* 简介区 */
.intro {
    padding: 48px 0;
    background: var(--surface);
    text-align: center;
    margin-bottom: 48px;
}

.section-title {
    font-size: 2.5rem;
    font-weight: 600;
    color: var(--text);
    margin-bottom: 24px;
}

.intro-text {
    max-width: 800px;
    margin: 0 auto;
    font-size: 1.1rem;
    color: var(--text-light);
    line-height: 1.8;
}

/* 特性区 */
.features-section {
    padding: 48px 0;
    margin-bottom: 48px;
}

.feature-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 32px;
    margin-top: 32px;
}

.feature-card {
    background: var(--background);
    padding: 40px 24px;
    border-radius: 12px;
    box-shadow: var(--shadow);
    text-align: center;
    transition: all 0.3s ease;
    border: 1px solid var(--border);
}

.feature-card:hover {
    transform: translateY(-8px);
    box-shadow: var(--shadow-xl);
    border-color: var(--primary);
}

.feature-icon {
    font-size: 3rem;
    margin-bottom: 16px;
}

.feature-card h3 {
    font-size: 1.5rem;
    margin-bottom: 12px;
    color: var(--text);
}

.feature-card p {
    color: var(--text-light);
    line-height: 1.6;
}

/* 为什么选择区 */
.why-section {
    padding: 48px 0;
    background: var(--surface);
    margin-bottom: 48px;
}

.why-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(350px, 1fr));
    gap: 24px;
    margin-top: 32px;
}

.why-item {
    background: var(--background);
    padding: 32px;
    border-radius: 12px;
    box-shadow: var(--shadow);
    display: flex;
    align-items: flex-start;
    gap: 16px;
    transition: all 0.3s ease;
}

.why-item:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-lg);
}

.why-icon {
    font-size: 2rem;
    flex-shrink: 0;
}

.why-item h3 {
    font-size: 1.2rem;
    margin-bottom: 8px;
    color: var(--text);
}

.why-item p {
    color: var(--text-light);
    line-height: 1.6;
}

/* 下载引导区 */
.download-cta {
    padding: 64px 0;
    background: linear-gradient(135deg, #4285f4, #34a853);
    color: white;
    text-align: center;
    margin-bottom: 48px;
}

.download-cta .section-title {
    color: white;
}

.cta-text {
    font-size: 1.2rem;
    margin-bottom: 32px;
    opacity: 0.95;
}

/* 下载页面头部 */
.download-hero {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    text-align: center;
    padding: 60px 0;
}

.download-title {
    font-size: 3rem;
    font-weight: 600;
    margin-bottom: 12px;
}

.download-subtitle {
    font-size: 1.5rem;
    margin-bottom: 8px;
}

.download-note {
    font-size: 1.1rem;
    opacity: 0.9;
}

/* 下载平台区 */
.download-platforms {
    padding: 48px 0;
    margin-bottom: 48px;
}

.download-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 32px;
}

.download-card {
    background: var(--background);
    padding: 40px 24px;
    border-radius: 12px;
    box-shadow: var(--shadow);
    text-align: center;
    border: 2px solid var(--border);
    transition: all 0.3s ease;
}

.download-card:hover {
    transform: translateY(-8px);
    box-shadow: var(--shadow-xl);
    border-color: var(--primary);
}

.os-icon {
    font-size: 4rem;
    margin-bottom: 16px;
}

.download-card h3 {
    font-size: 1.8rem;
    margin-bottom: 8px;
    color: var(--text);
}

.os-version {
    color: var(--text-muted);
    margin-bottom: 16px;
}

.features-list {
    text-align: left;
    margin-bottom: 24px;
    list-style: none;
}

.features-list li {
    padding: 8px 0;
    color: var(--text-light);
    border-bottom: 1px solid var(--border);
}

.features-list li:last-child {
    border-bottom: none;
}

/* 下载说明 */
.download-info {
    padding: 48px 0;
    background: var(--surface);
    margin-bottom: 48px;
}

.info-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 32px;
    margin-top: 32px;
}

.info-card {
    background: var(--background);
    padding: 32px;
    border-radius: 12px;
    box-shadow: var(--shadow);
}

.info-card h3 {
    font-size: 1.4rem;
    margin-bottom: 16px;
    color: var(--text);
}

.step-list {
    list-style-position: inside;
    line-height: 2;
    color: var(--text-light);
}

.step-list li {
    padding: 8px 0;
}

.info-list {
    list-style: none;
    line-height: 2;
}

.info-list li {
    padding: 8px 0;
    color: var(--text-light);
}

.info-list strong {
    color: var(--text);
}

/* 返回首页 */
.back-home {
    padding: 40px 0;
    text-align: center;
    margin-bottom: 48px;
}

.back-home p {
    font-size: 1.2rem;
    margin-bottom: 24px;
    color: var(--text-light);
}

/* 404错误页面 */
.error-page {
    padding: 80px 0;
    text-align: center;
}

.error-code {
    font-size: 8rem;
    font-weight: 700;
    color: var(--primary);
    line-height: 1;
    margin-bottom: 24px;
}

.error-title {
    font-size: 2.5rem;
    color: var(--text);
    margin-bottom: 24px;
}

.error-message {
    font-size: 1.2rem;
    color: var(--text-light);
    margin-bottom: 40px;
    line-height: 1.8;
    max-width: 600px;
    margin-left: auto;
    margin-right: auto;
}

.error-actions {
    display: flex;
    gap: 16px;
    justify-content: center;
    flex-wrap: wrap;
}

/* 推荐下载区 */
.recommendation {
    padding: 48px 0;
    background: var(--surface);
    margin-bottom: 48px;
}

.download-grid.mini {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 16px;
    margin-top: 32px;
}

.mini-download-card {
    background: var(--background);
    padding: 24px;
    border-radius: 8px;
    box-shadow: var(--shadow);
    text-align: center;
    text-decoration: none;
    color: var(--text);
    transition: all 0.3s ease;
    border: 1px solid var(--border);
}

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

.mini-icon {
    font-size: 2.5rem;
    margin-bottom: 8px;
}

.mini-download-card h3 {
    font-size: 1.2rem;
    margin-bottom: 4px;
}

.mini-download-card p {
    color: var(--text-muted);
    font-size: 0.9rem;
}

/* 帮助区 */
.help-section {
    padding: 48px 0;
    margin-bottom: 48px;
}

.help-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 24px;
    margin-top: 32px;
}

.help-card {
    background: var(--surface);
    padding: 24px;
    border-radius: 8px;
    border-left: 4px solid var(--primary);
}

.help-card h3 {
    font-size: 1.2rem;
    margin-bottom: 12px;
    color: var(--text);
}

.help-card p {
    color: var(--text-light);
    line-height: 1.6;
}

/* 页脚 */
.footer {
    background: var(--surface);
    border-top: 1px solid var(--border);
    padding: 32px 0;
    text-align: center;
}

.footer-links {
    display: flex;
    justify-content: center;
    gap: 24px;
    margin-bottom: 16px;
    flex-wrap: wrap;
}

.footer-links a {
    color: var(--text-light);
    text-decoration: none;
    transition: color 0.3s ease;
}

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

.footer-text {
    color: var(--text-muted);
    margin-bottom: 8px;
}

.footer-note {
    color: var(--text-muted);
    font-size: 0.9rem;
}

.footer-note a {
    color: var(--primary);
    text-decoration: none;
}

/* 响应式设计 */
@media (max-width: 768px) {
    .container {
        padding: 0 16px;
    }
    
    .navbar .container {
        flex-direction: column;
        gap: 12px;
    }
    
    .nav-menu {
        gap: 16px;
        flex-wrap: wrap;
        justify-content: center;
    }
    
    .hero-title,
    .download-title {
        font-size: 2.5rem;
    }
    
    .hero-subtitle,
    .download-subtitle {
        font-size: 1.3rem;
    }
    
    .hero,
    .download-hero {
        padding: 48px 0;
    }
    
    .section-title {
        font-size: 2rem;
    }
    
    .feature-grid,
    .why-grid,
    .download-grid {
        grid-template-columns: 1fr;
        gap: 24px;
    }
    
    .why-item {
        align-items: flex-start;
    }
    
    .info-grid,
    .help-grid {
        grid-template-columns: 1fr;
    }
    
    .hero-actions,
    .error-actions {
        flex-direction: column;
        align-items: center;
    }
    
    .btn {
        width: 100%;
        max-width: 300px;
    }
}

@media (max-width: 480px) {
    .hero-title,
    .download-title {
        font-size: 2rem;
    }
    
    .hero-subtitle,
    .download-subtitle {
        font-size: 1.1rem;
    }
    
    .section-title {
        font-size: 1.6rem;
    }
    
    .feature-card,
    .download-card,
    .info-card {
        padding: 24px 16px;
    }
    
    .error-code {
        font-size: 6rem;
    }
}

/* 动画效果 */
@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

body.loaded {
    opacity: 1;
}