:root {
    --primary-color: #007AFF;
    --primary-dark: #0051D5;
    --secondary-color: #5856D6;
    --text-primary: #1D1D1F;
    --text-secondary: #86868B;
    --bg-primary: #FFFFFF;
    --bg-secondary: #F5F5F7;
    --bg-dark: #000000;
    --border-color: #D2D2D7;
    --success-color: #34C759;
    --warning-color: #FF9500;
    --error-color: #FF3B30;
    --shadow: 0 2px 8px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 8px 24px rgba(0, 0, 0, 0.12);
    --navbar-bg: #1a1a2e;
    --navbar-text: #FFFFFF;
}

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

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
    color: var(--text-primary);
    background-color: var(--bg-primary);
    line-height: 1.6;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 2rem;
}

/* Navigation */
.navbar {
    background: linear-gradient(135deg, #1a1a2e 0%, #16213e 100%);
    border-bottom: 1px solid rgba(255, 255, 255, 0.1);
    position: sticky;
    top: 0;
    z-index: 1000;
    padding: 1rem 0;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.15);
}

.nav-wrapper {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    text-decoration: none;
    display: flex;
    align-items: center;
    height: 40px;
    gap: 0.75rem;
}

.logo-img {
    height: 40px;
    width: auto;
    display: block;
}

.logo-text {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--navbar-text);
}

.nav-menu {
    display: flex;
    list-style: none;
    gap: 2rem;
    align-items: center;
}

.nav-menu a {
    text-decoration: none;
    color: var(--navbar-text);
    font-weight: 500;
    font-size: 0.95rem;
    transition: color 0.2s;
    opacity: 0.9;
}

.nav-menu a:hover {
    color: #00CA4A;
    opacity: 1;
}

.logo-text {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--navbar-text);
    text-shadow: 0 2px 4px rgba(0, 0, 0, 0.2);
}

.github-link {
    background-color: var(--bg-dark);
    color: white !important;
    padding: 0.5rem 1rem;
    border-radius: 6px;
    transition: background-color 0.2s;
    font-weight: 500;
}

.github-link:hover {
    background-color: #333;
    color: white !important;
}

.mobile-menu-toggle {
    display: none;
    flex-direction: column;
    background: none;
    border: none;
    cursor: pointer;
    gap: 4px;
}

.mobile-menu-toggle span {
    width: 25px;
    height: 2px;
    background-color: var(--navbar-text);
    transition: all 0.3s;
}

/* Hero Section */
.hero {
    padding: 5rem 0 4rem;
    text-align: center;
    background: linear-gradient(135deg, #f8f9fa 0%, #e9ecef 100%);
    position: relative;
    overflow: hidden;
}

.hero::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: radial-gradient(circle at 50% 0%, rgba(0, 122, 255, 0.05) 0%, transparent 50%);
    pointer-events: none;
}

.hero-content {
    max-width: 900px;
    margin: 0 auto;
}

.hero-title {
    font-size: 3rem;
    font-weight: 700;
    margin-bottom: 1rem;
    color: var(--text-primary);
    line-height: 1.3;
}

.hero-subtitle {
    font-size: 1.5rem;
    color: var(--text-secondary);
    margin-bottom: 1.5rem;
    font-weight: 500;
}

.hero-description {
    font-size: 1.125rem;
    color: var(--text-secondary);
    margin-bottom: 2.5rem;
    line-height: 1.8;
}

.hero-buttons {
    display: flex;
    gap: 1rem;
    justify-content: center;
    margin-bottom: 2rem;
    flex-wrap: wrap;
}

.hero-badges {
    display: flex;
    gap: 0.75rem;
    justify-content: center;
    flex-wrap: wrap;
}

.badge {
    background-color: var(--bg-secondary);
    color: var(--text-primary);
    padding: 0.5rem 1rem;
    border-radius: 20px;
    font-size: 0.875rem;
    font-weight: 500;
}

/* Buttons */
.btn {
    display: inline-block;
    padding: 0.75rem 1.5rem;
    border-radius: 8px;
    text-decoration: none;
    font-weight: 600;
    font-size: 1rem;
    transition: all 0.2s;
    border: 2px solid transparent;
    cursor: pointer;
}

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

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

.btn-secondary {
    background-color: var(--bg-secondary);
    color: var(--text-primary);
}

.btn-secondary:hover {
    background-color: var(--border-color);
}

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

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

.btn-large {
    padding: 1rem 2rem;
    font-size: 1.125rem;
}

/* Features Preview */
.features-preview {
    padding: 3rem 0;
}

.section-title {
    font-size: 2.5rem;
    font-weight: 700;
    text-align: center;
    margin-bottom: 2rem;
    color: var(--text-primary);
}

.features-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 2rem;
    margin-bottom: 2rem;
}

.feature-card {
    background-color: var(--bg-primary);
    padding: 2rem;
    border-radius: 12px;
    border: 1px solid var(--border-color);
    transition: all 0.3s;
    display: flex;
    flex-direction: column;
}

.feature-card img {
    display: block;
    margin: 0 auto;
    max-width: 100%;
}

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

.feature-card-header {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    margin-bottom: 1rem;
    padding: 0.5rem 0.75rem;
    background-color: var(--bg-secondary);
    border-radius: 8px;
    width: fit-content;
}

.feature-icon {
    font-size: 2rem;
    line-height: 1;
    flex-shrink: 0;
}

.feature-card h3 {
    font-size: 1.25rem;
    font-weight: 600;
    margin: 0;
    color: var(--text-primary);
    flex: 1;
}

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

/* What is Section */
.what-is {
    padding: 3rem 0;
}

/* Platform Support */
.platform-support {
    padding: 3rem 0;
    background-color: var(--bg-secondary);
}

/* System Requirements */
.system-requirements {
    padding: 3rem 0;
}

.system-requirements ul {
    list-style: none;
    padding-left: 0;
}

.system-requirements li {
    margin-bottom: 0.5rem;
    padding-left: 1.5rem;
    position: relative;
}

.system-requirements li::before {
    content: "✓";
    position: absolute;
    left: 0;
    color: var(--success-color);
    font-weight: bold;
}

/* Key Features */
.key-features {
    padding: 3rem 0;
}

/* What is SideStore */
.what-is-sidestore {
    padding: 3rem 0;
}

.what-is-sidestore ul {
    list-style: none;
    padding-left: 0;
}

.what-is-sidestore li {
    margin-bottom: 0.75rem;
    padding-left: 1.5rem;
    position: relative;
}

.what-is-sidestore li::before {
    content: "•";
    position: absolute;
    left: 0;
    color: var(--primary-color);
    font-weight: bold;
    font-size: 1.5rem;
    line-height: 1.2;
}

/* Advantages */
.advantages {
    padding: 3rem 0;
}

/* FAQ Preview */
.faq-preview {
    padding: 3rem 0;
}

.faq-preview h3 {
    color: var(--text-primary);
    font-size: 1.25rem;
    font-weight: 600;
}

/* Quick Start */
.quick-start {
    padding: 3rem 0;
    background-color: var(--bg-secondary);
}

.steps {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 2rem;
    margin-bottom: 2rem;
}

.step {
    text-align: center;
    padding: 2rem;
}

.step-number {
    width: 60px;
    height: 60px;
    border-radius: 50%;
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    color: white;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.5rem;
    font-weight: 700;
    margin: 0 auto 1.5rem;
}

.step h3 {
    font-size: 1.25rem;
    font-weight: 600;
    margin-bottom: 0.75rem;
    color: var(--text-primary);
}

.step p {
    color: var(--text-secondary);
    line-height: 1.6;
    margin-bottom: 0.5rem;
}

.step p:last-child {
    margin-bottom: 0;
}

.step a {
    color: var(--primary-color);
    text-decoration: none;
    font-weight: 500;
}

.step a:hover {
    text-decoration: underline;
}

.step code {
    background-color: rgba(0, 0, 0, 0.05);
    padding: 0.2rem 0.5rem;
    border-radius: 4px;
    font-family: 'Monaco', 'Courier New', monospace;
    font-size: 0.9em;
}

/* CTA Section */
.cta-section {
    padding: 3rem 0;
    text-align: center;
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    color: white;
}

.cta-section h2 {
    font-size: 2.5rem;
    font-weight: 700;
    margin-bottom: 1rem;
}

.cta-section p {
    font-size: 1.25rem;
    margin-bottom: 2rem;
    opacity: 0.9;
}

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

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

/* Footer */
.footer {
    background-color: var(--bg-dark);
    color: white;
    padding: 3rem 0 1.5rem;
}

.footer-content {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 2rem;
    margin-bottom: 2rem;
}

.footer-section h3 {
    font-size: 1.25rem;
    margin-bottom: 1rem;
}

.footer-section h4 {
    font-size: 1rem;
    margin-bottom: 0.75rem;
    color: rgba(255, 255, 255, 0.8);
}

.footer-section p {
    color: rgba(255, 255, 255, 0.6);
    line-height: 1.6;
}

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

.footer-section ul li {
    margin-bottom: 0.5rem;
}

.footer-section a {
    color: rgba(255, 255, 255, 0.6);
    text-decoration: none;
    transition: color 0.2s;
}

.footer-section a:hover {
    color: white;
}

.footer-bottom {
    text-align: center;
    padding-top: 2rem;
    border-top: 1px solid rgba(255, 255, 255, 0.1);
    color: rgba(255, 255, 255, 0.6);
}

/* Utility Classes */
.text-center {
    text-align: center;
}

/* Page Specific Styles */
.page-header {
    padding: 4rem 0 2rem;
    background-color: var(--bg-secondary);
    text-align: center;
}

.page-header h1 {
    font-size: 3rem;
    font-weight: 700;
    margin-bottom: 1rem;
}

.page-header p {
    font-size: 1.25rem;
    color: var(--text-secondary);
}

.page-content {
    padding: 4rem 0;
    max-width: 900px;
    margin: 0 auto;
}

.page-content h2 {
    font-size: 2rem;
    font-weight: 600;
    margin-top: 3rem;
    margin-bottom: 1rem;
    color: var(--text-primary);
}

.page-content h3 {
    font-size: 1.5rem;
    font-weight: 600;
    margin-top: 2rem;
    margin-bottom: 0.75rem;
    color: var(--text-primary);
}

.page-content p {
    margin-bottom: 1rem;
    color: var(--text-secondary);
    line-height: 1.8;
}

.page-content ul, .page-content ol {
    margin-bottom: 1.5rem;
    padding-left: 2rem;
    color: var(--text-secondary);
}

.page-content li {
    margin-bottom: 0.5rem;
    line-height: 1.8;
}

.page-content code {
    background-color: var(--bg-secondary);
    padding: 0.2rem 0.5rem;
    border-radius: 4px;
    font-family: 'Monaco', 'Courier New', monospace;
    font-size: 0.9em;
}

.page-content pre {
    background-color: var(--bg-secondary);
    padding: 1rem;
    border-radius: 8px;
    overflow-x: auto;
    margin-bottom: 1.5rem;
}

.page-content pre code {
    background: none;
    padding: 0;
}

/* Download Page */
.download-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 2rem;
    margin-top: 3rem;
}

@media (max-width: 968px) {
    .download-grid {
        grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    }
}

/* OS Guide Sections */
.os-guide-section {
    scroll-margin-top: 100px;
    margin-bottom: 4rem;
    animation: fadeIn 0.3s ease-in;
    border-top: 2px solid var(--border-color);
    padding-top: 2rem;
}

.os-guide-section.active-guide {
    display: block;
}

.os-guide-section h3 {
    border-bottom: 3px solid var(--primary-color);
    padding-bottom: 0.75rem;
    margin-bottom: 1.5rem;
}

/* OS Tabs Container */
.os-tabs-container {
    width: 100%;
}

/* OS Tabs */
.os-tabs {
    display: flex;
    justify-content: flex-start;
    gap: 0;
    margin-bottom: 0;
    flex-wrap: wrap;
    border-bottom: 2px solid var(--border-color);
    padding: 0;
}

.os-tab-btn {
    padding: 1rem 2rem;
    border: none;
    border-bottom: 3px solid transparent;
    background-color: transparent;
    color: var(--text-secondary);
    border-radius: 0;
    cursor: pointer;
    font-size: 1rem;
    font-weight: 500;
    transition: all 0.2s;
    display: flex;
    align-items: center;
    font-family: inherit;
    position: relative;
    margin-bottom: -2px;
}

.os-tab-btn:hover {
    color: var(--text-primary);
    background-color: var(--bg-secondary);
}

.os-tab-btn.active {
    color: var(--primary-color);
    border-bottom-color: var(--primary-color);
    background-color: transparent;
}

.os-tab-btn.active:hover {
    color: var(--primary-color);
    border-bottom-color: var(--primary-color);
}

/* Tab Content Container */
.os-guide-section {
    border-top: none;
    margin-top: 0;
    padding-top: 0;
}

@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(10px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.download-card {
    background-color: var(--bg-primary);
    border: 2px solid var(--border-color);
    border-radius: 12px;
    padding: 2rem;
    text-align: center;
    transition: all 0.3s;
    display: flex;
    flex-direction: column;
    align-items: center;
}

.download-card img {
    display: block;
    margin: 0 auto;
    max-width: 100%;
}

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

.download-card-header {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    margin-bottom: 1rem;
    padding: 0.5rem 0.75rem;
    background-color: var(--bg-secondary);
    border-radius: 8px;
    width: fit-content;
    margin-left: auto;
    margin-right: auto;
}

.download-card .platform-icon {
    font-size: 2.5rem;
    line-height: 1;
    flex-shrink: 0;
}

.download-card h3 {
    font-size: 1.5rem;
    margin: 0;
    flex: 1;
}

.download-card p {
    color: var(--text-secondary);
    margin-bottom: 1.5rem;
}

/* Responsive Design */
@media (max-width: 768px) {
    .mobile-menu-toggle {
        display: flex;
    }

    .nav-menu {
        display: none;
        position: absolute;
        top: 100%;
        left: 0;
        right: 0;
        background: linear-gradient(135deg, #1a1a2e 0%, #16213e 100%);
        flex-direction: column;
        padding: 1rem;
        border-top: 1px solid rgba(255, 255, 255, 0.1);
        box-shadow: var(--shadow-lg);
    }

    .nav-menu.active {
        display: flex;
    }

    .hero-title {
        font-size: 2.5rem;
    }

    .hero-subtitle {
        font-size: 1.25rem;
    }

    .section-title {
        font-size: 2rem;
    }

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

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

    .container {
        padding: 0 1rem;
    }

    .hero-buttons {
        flex-direction: column;
    }

    .hero-buttons .btn {
        width: 100%;
    }
}