/* CSS Reset & Base */
*, *::before, *::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

:root {
    /* Light theme (default) */
    --color-bg: #ffffff;
    --color-bg-alt: #f8f9fa;
    --color-text: #1a1a1a;
    --color-text-muted: #6b7280;
    --color-border: #e5e7eb;
    --color-primary: #2563eb;
    --color-primary-hover: #1d4ed8;
    --color-accent: #10b981;

    /* Spacing */
    --space-xs: 0.5rem;
    --space-sm: 1rem;
    --space-md: 1.5rem;
    --space-lg: 2rem;
    --space-xl: 3rem;
    --space-2xl: 5rem;

    /* Typography */
    --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
    --font-mono: "SF Mono", Monaco, "Cascadia Code", "Roboto Mono", Consolas, monospace;

    /* Layout */
    --max-width: 900px;
    --border-radius: 8px;
}

/* Dark theme */
@media (prefers-color-scheme: dark) {
    :root {
        --color-bg: #0f0f0f;
        --color-bg-alt: #1a1a1a;
        --color-text: #f0f0f0;
        --color-text-muted: #9ca3af;
        --color-border: #2d2d2d;
        --color-primary: #3b82f6;
        --color-primary-hover: #60a5fa;
    }
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-sans);
    font-size: 16px;
    line-height: 1.6;
    color: var(--color-text);
    background-color: var(--color-bg);
}

/* Container */
.container {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 0 var(--space-md);
}

/* Typography */
h1, h2, h3 {
    font-weight: 600;
    line-height: 1.3;
}

h1 {
    font-size: 2.5rem;
}

h2 {
    font-size: 1.75rem;
    margin-bottom: var(--space-lg);
}

h3 {
    font-size: 1.125rem;
    margin-bottom: var(--space-xs);
}

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

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

a:hover {
    text-decoration: underline;
}

/* Buttons */
.btn {
    display: inline-flex;
    align-items: center;
    gap: var(--space-xs);
    padding: 0.75rem 1.5rem;
    border-radius: var(--border-radius);
    font-weight: 500;
    font-size: 1rem;
    text-decoration: none;
    transition: background-color 0.2s, transform 0.1s;
    cursor: pointer;
    border: none;
}

.btn:hover {
    text-decoration: none;
    transform: translateY(-1px);
}

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

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

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

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

.btn-download {
    background-color: var(--color-bg-alt);
    color: var(--color-text);
    border: 1px solid var(--color-border);
    min-width: 160px;
    justify-content: center;
}

.btn-download:hover {
    border-color: var(--color-primary);
    background-color: var(--color-bg);
    transform: none;
}

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

.site-header .container {
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 64px;
}

.logo {
    display: flex;
    align-items: center;
    gap: var(--space-xs);
    font-weight: 600;
    font-size: 1.25rem;
    color: var(--color-text);
    text-decoration: none;
}

.logo img {
    border-radius: 6px;
}

.logo:hover {
    text-decoration: none;
}

nav {
    display: flex;
    gap: var(--space-md);
}

nav a {
    color: var(--color-text-muted);
    font-size: 0.9rem;
}

nav a:hover {
    color: var(--color-text);
    text-decoration: none;
}

/* Hero */
.hero {
    padding: var(--space-2xl) 0;
    text-align: center;
}

.hero h1 {
    margin-bottom: var(--space-sm);
}

.hero-subtitle {
    font-size: 1.25rem;
    max-width: 600px;
    margin: 0 auto var(--space-lg);
}

.hero-cta {
    display: flex;
    gap: var(--space-sm);
    justify-content: center;
    margin-bottom: var(--space-xl);
}

.hero-image {
    margin-top: var(--space-lg);
}

.hero-image img {
    max-width: 100%;
    height: auto;
    border-radius: var(--border-radius);
    border: 1px solid var(--color-border);
    box-shadow: 0 4px 20px rgba(0, 0, 0, 0.1);
}

/* Why Section */
.why {
    padding: var(--space-xl) 0;
    background-color: var(--color-bg-alt);
}

.why p {
    font-size: 1.125rem;
    max-width: 700px;
}

/* Features */
.features {
    padding: var(--space-2xl) 0;
}

.features-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
    gap: var(--space-lg);
}

.feature {
    padding: var(--space-md);
    border-radius: var(--border-radius);
    background-color: var(--color-bg-alt);
}

.feature-icon {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 48px;
    height: 48px;
    background-color: var(--color-bg);
    border: 1px solid var(--color-border);
    border-radius: var(--border-radius);
    margin-bottom: var(--space-sm);
    color: var(--color-primary);
}

.feature h3 {
    color: var(--color-text);
}

/* How It Works */
.how-it-works {
    padding: var(--space-2xl) 0;
    background-color: var(--color-bg-alt);
}

.steps {
    display: flex;
    flex-direction: column;
    gap: var(--space-md);
    margin-bottom: var(--space-xl);
}

.step {
    display: flex;
    gap: var(--space-md);
    align-items: flex-start;
}

.step-number {
    flex-shrink: 0;
    display: flex;
    align-items: center;
    justify-content: center;
    width: 40px;
    height: 40px;
    background-color: var(--color-primary);
    color: white;
    font-weight: 600;
    border-radius: 50%;
}

.step-content h3 {
    color: var(--color-text);
}

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

.screenshot-showcase img {
    max-width: 100%;
    height: auto;
    border-radius: var(--border-radius);
    border: 1px solid var(--color-border);
    box-shadow: 0 4px 20px rgba(0, 0, 0, 0.1);
}

/* Download */
.download {
    padding: var(--space-2xl) 0;
    text-align: center;
}

.download-subtitle {
    margin-bottom: var(--space-lg);
    font-size: 1.125rem;
}

.download-buttons {
    display: flex;
    flex-wrap: wrap;
    gap: var(--space-sm);
    justify-content: center;
}

.download-buttons .btn.recommended {
    box-shadow: 0 0 0 2px var(--color-accent);
}

.download-hint {
    margin-top: var(--space-sm);
    font-size: 0.875rem;
    color: var(--color-accent);
}

.download-note {
    margin-top: var(--space-sm);
    font-size: 0.875rem;
}

/* Requirements */
.requirements {
    padding: var(--space-2xl) 0;
    background-color: var(--color-bg-alt);
}

.requirements-list {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: var(--space-lg);
}

.requirement {
    padding: var(--space-md);
    background-color: var(--color-bg);
    border: 1px solid var(--color-border);
    border-radius: var(--border-radius);
}

.requirement h3 {
    color: var(--color-text);
}

/* Contribute */
.contribute {
    padding: var(--space-2xl) 0;
    text-align: center;
}

.contribute p {
    font-size: 1.125rem;
    max-width: 600px;
    margin: 0 auto var(--space-lg);
}

.contribute-links {
    display: flex;
    gap: var(--space-sm);
    justify-content: center;
    flex-wrap: wrap;
}

/* Footer */
.site-footer {
    padding: var(--space-lg) 0;
    border-top: 1px solid var(--color-border);
    text-align: center;
}

.site-footer p {
    font-size: 0.9rem;
}

.site-footer a {
    color: var(--color-text-muted);
}

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

/* Responsive */
@media (max-width: 640px) {
    h1 {
        font-size: 2rem;
    }

    h2 {
        font-size: 1.5rem;
    }

    .hero {
        padding: var(--space-xl) 0;
    }

    .hero-subtitle {
        font-size: 1.1rem;
    }

    .hero-cta {
        flex-direction: column;
        align-items: center;
    }

    nav {
        display: none;
    }

    .download-buttons {
        flex-direction: column;
        align-items: center;
    }

    .btn-download {
        width: 100%;
        max-width: 280px;
    }
}