:root {
    --primary-color: #1a73e8;
    --primary-hover: #1557b0;
    --text-main: #202124;
    --text-muted: #5f6368;
    --bg-light: #f8f9fa;
    --bg-white: #ffffff;
    --border-color: #dadce0;
    --success-color: #1e8e3e;
    --shadow-sm: 0 1px 2px 0 rgba(60,64,67,0.3), 0 1px 3px 1px rgba(60,64,67,0.15);
    --shadow-md: 0 4px 6px -1px rgba(0,0,0,0.1), 0 2px 4px -1px rgba(0,0,0,0.06);
}

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

body {
    font-family: 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    color: var(--text-main);
    background-color: var(--bg-white);
    line-height: 1.6;
    -webkit-font-smoothing: antialiased;
}

a {
    color: var(--primary-color);
    text-decoration: none;
    transition: color 0.2s;
}

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

/* Header & Navigation */
.site-header {
    position: sticky;
    top: 0;
    background-color: var(--bg-white);
    box-shadow: var(--shadow-sm);
    z-index: 1000;
}

.nav-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    height: 70px;
}

.brand {
    display: flex;
    align-items: center;
    gap: 12px;
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--text-main);
}

.brand svg {
    width: 32px;
    height: 32px;
}

.nav-links {
    display: flex;
    gap: 30px;
}

.nav-links a {
    color: var(--text-muted);
    font-weight: 500;
    padding: 24px 0;
    position: relative;
}

.nav-links a:hover {
    color: var(--text-main);
}

.nav-links a.active {
    color: var(--primary-color);
}

.nav-links a.active::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 100%;
    height: 3px;
    background-color: var(--primary-color);
    border-radius: 3px 3px 0 0;
}

/* Buttons */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 12px 28px;
    font-size: 1rem;
    font-weight: 600;
    border-radius: 24px;
    border: none;
    cursor: pointer;
    transition: all 0.2s ease;
    text-align: center;
}

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

.btn-primary, a.btn-primary {
    background-color: var(--primary-color);
    color: #fff;
    box-shadow: 0 1px 3px rgba(0,0,0,0.1);
}

.btn-primary:hover:not(:disabled), a.btn-primary:hover {
    background-color: var(--primary-hover);
    color: #fff;
    box-shadow: 0 2px 6px rgba(0,0,0,0.2);
}

.btn-outline {
    background-color: transparent;
    color: var(--primary-color);
    border: 2px solid var(--border-color);
}

.btn-outline:hover:not(:disabled) {
    background-color: var(--bg-light);
    border-color: var(--primary-color);
}

.btn-large {
    padding: 16px 40px;
    font-size: 1.1rem;
    border-radius: 30px;
}

/* Layout Blocks */
.section {
    padding: 80px 20px;
}

.section-bg-light {
    background-color: var(--bg-light);
}

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

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

.section-title {
    font-size: 2.5rem;
    font-weight: 700;
    margin-bottom: 20px;
    color: var(--text-main);
}

.section-desc {
    font-size: 1.1rem;
    color: var(--text-muted);
    max-width: 700px;
    margin: 0 auto 50px;
}

/* Hero Section */
.hero {
    padding: 100px 20px;
    text-align: center;
    background: linear-gradient(135deg, #f8f9fa 0%, #e8f0fe 100%);
    overflow: hidden;
}

.hero h1 {
    font-size: 3.5rem;
    font-weight: 800;
    line-height: 1.2;
    margin-bottom: 24px;
    letter-spacing: -0.5px;
}

.hero p {
    font-size: 1.25rem;
    color: var(--text-muted);
    max-width: 800px;
    margin: 0 auto 40px;
}

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

/* Features Grid */
.features-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 40px;
    margin-top: 60px;
}

.feature-card {
    background: var(--bg-white);
    padding: 40px 30px;
    border-radius: 16px;
    box-shadow: var(--shadow-sm);
    transition: transform 0.3s ease;
    border: 1px solid var(--border-color);
    text-align: center;
}

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

.feature-icon {
    width: 64px;
    height: 64px;
    margin: 0 auto 24px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: #e8f0fe;
    border-radius: 50%;
    color: var(--primary-color);
}

.feature-icon svg {
    width: 32px;
    height: 32px;
}

.feature-card h3 {
    font-size: 1.5rem;
    margin-bottom: 16px;
}

.feature-card p {
    color: var(--text-muted);
}

/* FAQ Section */
.faq-list {
    max-width: 800px;
    margin: 0 auto;
}

.faq-item {
    border-bottom: 1px solid var(--border-color);
    padding: 24px 0;
}

.faq-item:first-child {
    border-top: 1px solid var(--border-color);
}

.faq-question {
    font-size: 1.25rem;
    font-weight: 600;
    margin-bottom: 12px;
    color: var(--text-main);
}

.faq-answer {
    color: var(--text-muted);
    line-height: 1.6;
}

/* Featured Download Block */
.featured-download {
    background: #fff;
    border: 2px solid var(--primary-color);
    border-radius: 24px;
    padding: 60px 40px;
    text-align: center;
    box-shadow: 0 12px 32px rgba(26,115,232,0.15);
    margin-bottom: 40px;
    position: relative;
    overflow: hidden;
    max-width: 800px;
    margin-left: auto;
    margin-right: auto;
}

.featured-download::before {
    content: '强烈推荐';
    position: absolute;
    top: 24px;
    right: -45px;
    background: var(--primary-color);
    color: white;
    padding: 8px 50px;
    font-size: 1rem;
    font-weight: bold;
    transform: rotate(45deg);
    box-shadow: 0 2px 4px rgba(0,0,0,0.2);
}

.featured-download .dl-icon {
    width: 100px;
    height: 100px;
    color: var(--primary-color);
}

.featured-download h3 {
    font-size: 2rem;
    margin-bottom: 16px;
    color: var(--text-main);
}

.featured-download p {
    font-size: 1.2rem;
    color: var(--text-muted);
    margin-bottom: 32px;
}

.featured-download .btn {
    font-size: 1.2rem;
    padding: 16px 48px;
    border-radius: 30px;
}

/* Download Cards */
.download-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 30px;
    margin-top: 40px;
}

.dl-card {
    padding: 40px 30px;
    border-radius: 20px;
    text-align: center;
    background: #fff;
    border: 1px solid var(--border-color);
    position: relative;
    overflow: hidden;
}

.dl-card.highlight {
    border: 2px solid var(--primary-color);
    box-shadow: 0 8px 24px rgba(26,115,232,0.15);
}

.dl-card.highlight::before {
    content: '推荐';
    position: absolute;
    top: 12px;
    right: -30px;
    background: var(--primary-color);
    color: white;
    padding: 4px 30px;
    font-size: 0.8rem;
    font-weight: bold;
    transform: rotate(45deg);
}

.dl-icon {
    width: 80px;
    height: 80px;
    margin: 0 auto 20px;
    color: var(--text-main);
}

.dl-icon svg {
    width: 100%;
    height: 100%;
}

.dl-card h3 {
    font-size: 1.5rem;
    margin-bottom: 10px;
}

.dl-card p {
    color: var(--text-muted);
    margin-bottom: 24px;
    font-size: 0.95rem;
}

/* Content Article */
.article-content {
    max-width: 800px;
    margin: 0 auto;
}

.article-content h2 {
    font-size: 2rem;
    margin: 40px 0 20px;
    color: var(--text-main);
}

.article-content h3 {
    font-size: 1.5rem;
    margin: 30px 0 16px;
}

.article-content p {
    margin-bottom: 20px;
    font-size: 1.1rem;
    color: #3c4043;
}

.article-content ul {
    margin-bottom: 20px;
    padding-left: 24px;
}

.article-content li {
    font-size: 1.1rem;
    margin-bottom: 10px;
    color: #3c4043;
}

.cta-box {
    background: #e8f0fe;
    padding: 40px;
    border-radius: 16px;
    text-align: center;
    margin-top: 50px;
}

.cta-box h3 {
    font-size: 1.8rem;
    margin-bottom: 16px;
    color: var(--primary-color);
}

/* Footer */
.site-footer {
    background-color: #202124;
    color: #9aa0a6;
    padding: 60px 20px 40px;
    text-align: center;
    font-size: 0.9rem;
}

.footer-safe {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    color: var(--success-color);
    background: rgba(30,142,62,0.1);
    padding: 8px 16px;
    border-radius: 20px;
    margin-bottom: 24px;
    font-weight: 500;
}

.footer-text {
    max-width: 800px;
    margin: 0 auto;
    line-height: 1.6;
}

/* Spin Animation */
@keyframes spin { 
    from { transform: rotate(0deg); } 
    to { transform: rotate(360deg); } 
}

/* Responsive */
@media (max-width: 768px) {
    .hero h1 { font-size: 2.5rem; }
    .hero p { font-size: 1.1rem; }
    .nav-links { gap: 16px; }
    .nav-links a { font-size: 0.9rem; padding: 24px 0; }
    .section { padding: 50px 20px; }
    .section-title { font-size: 2rem; }
}