/* ==========================================================================
   Antigravity Core Design System & Theme Engine
   ========================================================================== */

:root {
    /* Color Palette - Dark Mode Default */
    --bg-base: #080c14;
    --bg-surface: #0f172a;
    --bg-surface-elevated: #1e293b;
    --bg-glass: rgba(15, 23, 42, 0.75);
    --border-subtle: rgba(255, 255, 255, 0.08);
    --border-focus: rgba(99, 102, 241, 0.5);

    /* Text Colors */
    --text-primary: #f8fafc;
    --text-secondary: #94a3b8;
    --text-muted: #64748b;
    --text-inverse: #0f172a;

    /* Accents & Highlights */
    --primary: #6366f1;
    --primary-hover: #4f46e5;
    --primary-glow: rgba(99, 102, 241, 0.35);

    --secondary: #a855f7;
    --accent: #06b6d4;
    --success: #10b981;
    --warning: #f59e0b;
    --danger: #ef4444;

    /* Gradients */
    --gradient-brand: linear-gradient(135deg, #6366f1 0%, #a855f7 50%, #ec4899 100%);
    --gradient-glow: radial-gradient(circle at 50% 0%, rgba(99, 102, 241, 0.15) 0%, transparent 70%);
    --gradient-card: linear-gradient(180deg, rgba(30, 41, 59, 0.7) 0%, rgba(15, 23, 42, 0.8) 100%);

    /* Typography & Sizing */
    --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Helvetica, Arial, sans-serif;
    --font-mono: 'JetBrains Mono', 'Fira Code', Menlo, Consolas, monospace;

    /* Shadows & Radii */
    --radius-sm: 6px;
    --radius-md: 10px;
    --radius-lg: 16px;
    --radius-xl: 24px;

    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.3);
    --shadow-md: 0 4px 12px -2px rgba(0, 0, 0, 0.4);
    --shadow-lg: 0 12px 28px -6px rgba(0, 0, 0, 0.5);
    --shadow-glow: 0 0 24px var(--primary-glow);

    /* Transitions */
    --transition-fast: 150ms cubic-bezier(0.4, 0, 0.2, 1);
    --transition-base: 250ms cubic-bezier(0.4, 0, 0.2, 1);
}

/* Light Theme Variables */
[data-theme="light"] {
    --bg-base: #f8fafc;
    --bg-surface: #ffffff;
    --bg-surface-elevated: #f1f5f9;
    --bg-glass: rgba(255, 255, 255, 0.85);
    --border-subtle: rgba(0, 0, 0, 0.08);
    --border-focus: rgba(99, 102, 241, 0.4);

    --text-primary: #0f172a;
    --text-secondary: #475569;
    --text-muted: #94a3b8;
    --text-inverse: #ffffff;

    --gradient-card: linear-gradient(180deg, rgba(255, 255, 255, 0.9) 0%, rgba(241, 245, 249, 0.9) 100%);
    --shadow-sm: 0 1px 3px 0 rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 12px -2px rgba(0, 0, 0, 0.08);
    --shadow-lg: 0 12px 28px -6px rgba(0, 0, 0, 0.12);
}

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

html {
    font-family: var(--font-sans);
    background-color: var(--bg-base);
    color: var(--text-primary);
    line-height: 1.6;
    scroll-behavior: smooth;
    min-height: 100%;
}

body {
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    background-color: var(--bg-base);
    background-image: var(--gradient-glow);
    background-repeat: no-repeat;
    background-attachment: fixed;
    transition: background-color var(--transition-base), color var(--transition-base);
}

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

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

img, svg {
    display: block;
    max-width: 100%;
}

code, pre {
    font-family: var(--font-mono);
}

/* ==========================================================================
   Layout Containers & Grid
   ========================================================================== */
.container {
    width: 100%;
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 1.5rem;
}

.site-header {
    position: sticky;
    top: 0;
    z-index: 50;
    background: var(--bg-glass);
    backdrop-filter: blur(14px);
    -webkit-backdrop-filter: blur(14px);
    border-bottom: 1px solid var(--border-subtle);
}

.nav-wrapper {
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 70px;
}

.brand-logo {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    font-weight: 700;
    font-size: 1.25rem;
    color: var(--text-primary);
    letter-spacing: -0.02em;
}

.brand-logo .brand-icon {
    width: 34px;
    height: 34px;
    border-radius: var(--radius-sm);
    background: var(--gradient-brand);
    display: flex;
    align-items: center;
    justify-content: center;
    color: #fff;
    box-shadow: var(--shadow-glow);
}

.nav-links {
    display: flex;
    align-items: center;
    gap: 1.5rem;
    list-style: none;
}

.nav-link {
    color: var(--text-secondary);
    font-weight: 500;
    font-size: 0.95rem;
    padding: 0.5rem 0.75rem;
    border-radius: var(--radius-sm);
    transition: all var(--transition-fast);
}

.nav-link:hover, .nav-link.active {
    color: var(--text-primary);
    background: var(--bg-surface-elevated);
}

.nav-actions {
    display: flex;
    align-items: center;
    gap: 0.75rem;
}

/* Main Content Area */
.main-content {
    flex: 1;
    padding: 2.5rem 0 4rem;
}

/* Footer */
.site-footer {
    border-top: 1px solid var(--border-subtle);
    background: var(--bg-surface);
    padding: 2rem 0;
    margin-top: auto;
    font-size: 0.9rem;
    color: var(--text-muted);
}

.footer-inner {
    display: flex;
    align-items: center;
    justify-content: space-between;
    flex-wrap: wrap;
    gap: 1rem;
}

/* ==========================================================================
   Typography Utilities
   ========================================================================== */
h1, h2, h3, h4, h5, h6 {
    color: var(--text-primary);
    font-weight: 700;
    line-height: 1.25;
    letter-spacing: -0.02em;
}

.title-hero {
    font-size: 2.75rem;
    margin-bottom: 0.75rem;
}

.text-gradient {
    background: var(--gradient-brand);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}

.subtitle-hero {
    font-size: 1.15rem;
    color: var(--text-secondary);
    max-width: 650px;
    margin-bottom: 2rem;
}

/* Grid System */
.grid {
    display: grid;
    gap: 1.5rem;
}

.grid-cols-1 { grid-template-columns: repeat(1, minmax(0, 1fr)); }
.grid-cols-2 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
.grid-cols-3 { grid-template-columns: repeat(3, minmax(0, 1fr)); }
.grid-cols-4 { grid-template-columns: repeat(4, minmax(0, 1fr)); }

@media (max-width: 900px) {
    .grid-cols-3, .grid-cols-4 {
        grid-template-columns: repeat(2, minmax(0, 1fr));
    }
    .title-hero {
        font-size: 2rem;
    }
}

@media (max-width: 640px) {
    .grid-cols-2, .grid-cols-3, .grid-cols-4 {
        grid-template-columns: 1fr;
    }
    .nav-links {
        display: none;
    }
}