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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'PingFang SC', 'Hiragino Sans GB', 'Microsoft YaHei', sans-serif;
    line-height: 1.6;
    color: #202124;
    background-color: #fff;
}

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

.header {
    background: #fff;
    box-shadow: 0 1px 3px rgba(0, 0, 0, 0.1);
    position: sticky;
    top: 0;
    z-index: 100;
}

.header .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 16px 24px;
}

.logo {
    display: flex;
    align-items: center;
    gap: 12px;
    font-size: 20px;
    font-weight: 600;
    color: #202124;
}

.nav {
    display: flex;
    gap: 32px;
}

.nav-link {
    color: #5f6368;
    text-decoration: none;
    font-weight: 500;
    transition: color 0.2s;
    padding: 8px 0;
    position: relative;
}

.nav-link:hover {
    color: #4285f4;
}

.nav-link.active {
    color: #4285f4;
}

.nav-link.active::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    right: 0;
    height: 3px;
    background: #4285f4;
    border-radius: 2px 2px 0 0;
}

.hero {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    padding: 80px 0;
}

.hero .container {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 60px;
    align-items: center;
}

.hero-content h1 {
    font-size: 48px;
    font-weight: 700;
    margin-bottom: 16px;
}

.hero-subtitle {
    font-size: 24px;
    margin-bottom: 24px;
    opacity: 0.95;
}

.hero-description {
    font-size: 16px;
    line-height: 1.8;
    margin-bottom: 32px;
    opacity: 0.9;
}

.cta-button {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    background: white;
    color: #667eea;
    padding: 16px 32px;
    border-radius: 8px;
    text-decoration: none;
    font-weight: 600;
    font-size: 18px;
    transition: transform 0.2s, box-shadow 0.2s;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.15);
}

.cta-button:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(0, 0, 0, 0.2);
}

.features {
    padding: 80px 0;
    background: #f8f9fa;
}

.section-title {
    text-align: center;
    font-size: 36px;
    font-weight: 700;
    margin-bottom: 60px;
    color: #202124;
}

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

.feature-card {
    background: white;
    padding: 32px;
    border-radius: 12px;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.08);
    transition: transform 0.2s, box-shadow 0.2s;
}

.feature-card:hover {
    transform: translateY(-4px);
    box-shadow: 0 8px 24px rgba(0, 0, 0, 0.12);
}

.feature-icon {
    margin-bottom: 20px;
}

.feature-card h3 {
    font-size: 22px;
    font-weight: 600;
    margin-bottom: 12px;
    color: #202124;
}

.feature-card p {
    color: #5f6368;
    line-height: 1.7;
}

.stats {
    padding: 60px 0;
    background: linear-gradient(135deg, #4285f4 0%, #34a853 100%);
    color: white;
}

.stats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 40px;
    text-align: center;
}

.stat-number {
    font-size: 48px;
    font-weight: 700;
    margin-bottom: 8px;
}

.stat-label {
    font-size: 18px;
    opacity: 0.95;
}

.faq {
    padding: 80px 0;
    background: white;
}

.faq-list {
    max-width: 900px;
    margin: 0 auto;
}

.faq-item {
    background: #f8f9fa;
    border-radius: 8px;
    margin-bottom: 16px;
    overflow: hidden;
    transition: box-shadow 0.2s;
}

.faq-item:hover {
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.08);
}

.faq-question {
    display: flex;
    align-items: center;
    gap: 12px;
    padding: 20px 24px;
    cursor: pointer;
    user-select: none;
}

.faq-question h3 {
    flex: 1;
    font-size: 18px;
    font-weight: 600;
    color: #202124;
}

.faq-arrow {
    transition: transform 0.3s;
    flex-shrink: 0;
}

.faq-item.active .faq-arrow {
    transform: rotate(180deg);
}

.faq-answer {
    max-height: 0;
    overflow: hidden;
    transition: max-height 0.3s ease-out, padding 0.3s ease-out;
}

.faq-item.active .faq-answer {
    max-height: 1000px;
    padding: 0 24px 20px 60px;
}

.faq-answer p {
    color: #5f6368;
    line-height: 1.8;
}

.faq-answer a {
    color: #4285f4;
    text-decoration: none;
}

.faq-answer a:hover {
    text-decoration: underline;
}

.faq-answer strong {
    color: #202124;
    font-weight: 600;
}

.faq-answer code {
    background: #f1f3f4;
    padding: 2px 6px;
    border-radius: 3px;
    font-family: 'Courier New', monospace;
    font-size: 14px;
}

.cta-section {
    padding: 80px 0;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    text-align: center;
}

.cta-section h2 {
    font-size: 40px;
    font-weight: 700;
    margin-bottom: 16px;
}

.cta-section p {
    font-size: 20px;
    margin-bottom: 32px;
    opacity: 0.95;
}

.cta-button-large {
    display: inline-flex;
    align-items: center;
    gap: 12px;
    background: white;
    color: #667eea;
    padding: 20px 48px;
    border-radius: 12px;
    text-decoration: none;
    font-weight: 700;
    font-size: 20px;
    transition: transform 0.2s, box-shadow 0.2s;
    box-shadow: 0 6px 20px rgba(0, 0, 0, 0.2);
}

.cta-button-large:hover {
    transform: translateY(-3px);
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.25);
}

.footer {
    background: #202124;
    color: #9aa0a6;
    padding: 60px 0 20px;
}

.footer-content {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 40px;
    margin-bottom: 40px;
}

.footer-section h4 {
    color: #e8eaed;
    font-size: 16px;
    font-weight: 600;
    margin-bottom: 16px;
}

.footer-section ul {
    list-style: none;
}

.footer-section li {
    margin-bottom: 12px;
}

.footer-section a {
    color: #9aa0a6;
    text-decoration: none;
    transition: color 0.2s;
}

.footer-section a:hover {
    color: #4285f4;
}

.footer-bottom {
    border-top: 1px solid #3c4043;
    padding-top: 20px;
    text-align: center;
    font-size: 14px;
}

.download-hero {
    background: linear-gradient(135deg, #4285f4 0%, #34a853 100%);
    color: white;
    padding: 60px 0;
    text-align: center;
}

.download-hero h1 {
    font-size: 42px;
    font-weight: 700;
    margin-bottom: 12px;
}

.download-subtitle {
    font-size: 20px;
    opacity: 0.95;
}

.download-platforms {
    padding: 60px 0;
    background: #f8f9fa;
}

.platform-tabs {
    display: flex;
    justify-content: center;
    gap: 16px;
    margin-bottom: 48px;
    flex-wrap: wrap;
}

.platform-tab {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 8px;
    padding: 20px 32px;
    background: white;
    border: 2px solid #e0e0e0;
    border-radius: 12px;
    cursor: pointer;
    transition: all 0.2s;
    font-weight: 600;
    color: #5f6368;
}

.platform-tab:hover {
    border-color: #4285f4;
    color: #4285f4;
}

.platform-tab.active {
    background: #4285f4;
    border-color: #4285f4;
    color: white;
}

.platform-content {
    position: relative;
}

.platform-panel {
    display: none;
}

.platform-panel.active {
    display: block;
}

.download-card {
    background: white;
    border-radius: 16px;
    box-shadow: 0 4px 16px rgba(0, 0, 0, 0.1);
    overflow: hidden;
    margin-bottom: 32px;
}

.download-card.featured {
    border: 3px solid #4285f4;
}

.download-card-header {
    display: flex;
    align-items: center;
    gap: 24px;
    padding: 32px;
    background: linear-gradient(135deg, #f8f9fa 0%, #e8f0fe 100%);
}

.download-card-header h2 {
    font-size: 28px;
    font-weight: 700;
    margin-bottom: 4px;
    color: #202124;
}

.version-info {
    color: #5f6368;
    font-size: 14px;
}

.download-card-body {
    padding: 32px;
}

.feature-list {
    list-style: none;
    margin-bottom: 32px;
}

.feature-list li {
    display: flex;
    align-items: flex-start;
    gap: 12px;
    margin-bottom: 16px;
    color: #5f6368;
    line-height: 1.6;
}

.feature-list svg {
    flex-shrink: 0;
    margin-top: 2px;
}

.download-button {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 12px;
    width: 100%;
    padding: 16px 32px;
    border: none;
    border-radius: 8px;
    font-size: 18px;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.2s;
}

.download-button.primary {
    background: #4285f4;
    color: white;
}

.download-button.primary:hover {
    background: #3367d6;
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(66, 133, 244, 0.3);
}

.download-button.primary:disabled {
    background: #9aa0a6;
    cursor: not-allowed;
    transform: none;
}

.download-button.secondary {
    background: #f1f3f4;
    color: #202124;
}

.download-button.secondary:hover {
    background: #e8eaed;
}

.download-note {
    text-align: center;
    color: #5f6368;
    font-size: 14px;
    margin-top: 16px;
}

.system-requirements {
    background: #f8f9fa;
    padding: 32px;
    border-radius: 12px;
}

.system-requirements h3 {
    display: flex;
    align-items: center;
    gap: 12px;
    font-size: 22px;
    font-weight: 600;
    margin-bottom: 20px;
    color: #202124;
}

.system-requirements ul {
    list-style: none;
}

.system-requirements li {
    padding: 12px 0;
    border-bottom: 1px solid #e0e0e0;
    color: #5f6368;
    line-height: 1.6;
}

.system-requirements li:last-child {
    border-bottom: none;
}

.system-requirements strong {
    color: #202124;
    font-weight: 600;
}

.linux-intro {
    color: #5f6368;
    margin-bottom: 24px;
    line-height: 1.7;
}

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

.linux-package {
    background: #f8f9fa;
    padding: 24px;
    border-radius: 12px;
}

.linux-package h4 {
    font-size: 18px;
    font-weight: 600;
    margin-bottom: 8px;
    color: #202124;
}

.linux-package p {
    color: #5f6368;
    font-size: 14px;
    margin-bottom: 16px;
    line-height: 1.6;
}

.install-instructions {
    background: #f8f9fa;
    padding: 24px;
    border-radius: 12px;
}

.install-instructions h4 {
    font-size: 18px;
    font-weight: 600;
    margin-bottom: 16px;
    color: #202124;
}

.code-block {
    margin-bottom: 16px;
}

.code-block p {
    margin-bottom: 8px;
    color: #5f6368;
    font-weight: 600;
}

.code-block code {
    display: block;
    background: #202124;
    color: #34a853;
    padding: 12px 16px;
    border-radius: 6px;
    font-family: 'Courier New', monospace;
    font-size: 14px;
    overflow-x: auto;
}

.mobile-downloads {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(450px, 1fr));
    gap: 32px;
}

.download-faq {
    padding: 80px 0;
    background: white;
}

.install-guide {
    padding: 80px 0;
    background: #f8f9fa;
}

.guide-steps {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 32px;
}

.guide-step {
    text-align: center;
}

.step-number {
    margin-bottom: 20px;
    display: flex;
    justify-content: center;
}

.guide-step h3 {
    font-size: 22px;
    font-weight: 600;
    margin-bottom: 12px;
    color: #202124;
}

.guide-step p {
    color: #5f6368;
    line-height: 1.7;
}

@media (max-width: 768px) {
    .hero .container {
        grid-template-columns: 1fr;
        gap: 40px;
    }

    .hero-content h1 {
        font-size: 36px;
    }

    .hero-subtitle {
        font-size: 20px;
    }

    .hero-image {
        display: none;
    }

    .features-grid {
        grid-template-columns: 1fr;
    }

    .stats-grid {
        grid-template-columns: repeat(2, 1fr);
    }

    .section-title {
        font-size: 28px;
    }

    .platform-tabs {
        gap: 8px;
    }

    .platform-tab {
        padding: 16px 20px;
        font-size: 14px;
    }

    .platform-tab svg {
        width: 24px;
        height: 24px;
    }

    .download-card-header {
        flex-direction: column;
        text-align: center;
    }

    .mobile-downloads {
        grid-template-columns: 1fr;
    }

    .linux-downloads {
        grid-template-columns: 1fr;
    }

    .footer-content {
        grid-template-columns: repeat(2, 1fr);
    }
}

@media (max-width: 480px) {
    .hero-content h1 {
        font-size: 28px;
    }

    .hero-subtitle {
        font-size: 18px;
    }

    .cta-button {
        font-size: 16px;
        padding: 14px 24px;
    }

    .stats-grid {
        grid-template-columns: 1fr;
    }

    .stat-number {
        font-size: 36px;
    }

    .footer-content {
        grid-template-columns: 1fr;
    }

    .guide-steps {
        grid-template-columns: 1fr;
    }
}