/* ===================================
   CSS Variables & Reset
   =================================== */
:root {
    /* Colors */
    --color-primary: #2563eb;
    --color-secondary: #8b5cf6;
    --color-accent: #10b981;
    --color-warning: #f59e0b;
    --color-danger: #ef4444;

    /* Backgrounds */
    --color-bg-dark: #0f172a;
    --color-bg-card: #1e293b;
    --color-bg-elevated: #334155;
    --color-bg-hero: #1a2332;

    /* Text */
    --color-text-primary: #f1f5f9;
    --color-text-secondary: #cbd5e1;
    --color-text-muted: #94a3b8;

    /* Gradients */
    --gradient-quantum: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    --gradient-hero: linear-gradient(135deg, rgba(102, 126, 234, 0.1) 0%, rgba(118, 75, 162, 0.1) 100%);
    --gradient-card: linear-gradient(135deg, rgba(102, 126, 234, 0.05) 0%, rgba(118, 75, 162, 0.05) 100%);

    /* Spacing */
    --spacing-xs: 0.25rem;
    --spacing-sm: 0.5rem;
    --spacing-md: 1rem;
    --spacing-lg: 1.5rem;
    --spacing-xl: 2rem;
    --spacing-2xl: 3rem;
    --spacing-3xl: 4rem;

    /* Border Radius */
    --radius-sm: 0.375rem;
    --radius-md: 0.75rem;
    --radius-lg: 1rem;
    --radius-xl: 1.5rem;

    /* Shadows */
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.3);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.3), 0 2px 4px -1px rgba(0, 0, 0, 0.2);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.3), 0 4px 6px -2px rgba(0, 0, 0, 0.2);
    --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.3), 0 10px 10px -5px rgba(0, 0, 0, 0.2);
    --shadow-quantum: 0 0 20px rgba(102, 126, 234, 0.3);

    /* Transitions */
    --transition-fast: 150ms ease-in-out;
    --transition-base: 250ms ease-in-out;
    --transition-slow: 400ms ease-in-out;

    /* Fonts */
    --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
    --font-mono: 'JetBrains Mono', 'Courier New', monospace;
}

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

html {
    font-size: 16px;
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-sans);
    background-color: var(--color-bg-dark);
    color: var(--color-text-primary);
    line-height: 1.6;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

/* ===================================
   Typography
   =================================== */
h1, h2, h3, h4, h5, h6 {
    font-weight: 600;
    line-height: 1.2;
    color: var(--color-text-primary);
}

h1 { font-size: 2.5rem; }
h2 { font-size: 2rem; }
h3 { font-size: 1.5rem; }
h4 { font-size: 1.25rem; }

p {
    margin-bottom: var(--spacing-md);
    color: var(--color-text-secondary);
}

/* ===================================
   Layout Components
   =================================== */
.container {
    max-width: 1400px;
    margin: 0 auto;
    padding: 0 var(--spacing-lg);
}

/* Header */
.header {
    background: var(--color-bg-card);
    border-bottom: 1px solid var(--color-bg-elevated);
    padding: var(--spacing-lg) 0;
    position: sticky;
    top: 0;
    z-index: 100;
    backdrop-filter: blur(10px);
    box-shadow: var(--shadow-md);
}

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

.logo {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
}

.logo-image {
    height: 50px;
    width: auto;
}

.logo-emoji {
    font-size: 2rem;
    animation: pulse 2s ease-in-out infinite;
}

.logo h1 {
    margin: 0;
    background: var(--gradient-quantum);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    font-size: 1.8rem;
}

.quantum-badge {
    background: var(--gradient-quantum);
    color: white;
    padding: var(--spacing-xs) var(--spacing-md);
    border-radius: var(--radius-lg);
    font-size: 0.875rem;
    font-weight: 600;
    box-shadow: var(--shadow-quantum);
    animation: glow 2s ease-in-out infinite;
}

/* Language Switcher */
.language-switcher {
    display: flex;
    gap: var(--spacing-sm);
    align-items: center;
}

.lang-btn {
    padding: var(--spacing-xs) var(--spacing-md);
    border-radius: var(--radius-sm);
    background: var(--color-bg-elevated);
    color: var(--color-text-secondary);
    text-decoration: none;
    font-size: 0.875rem;
    font-weight: 600;
    transition: all var(--transition-fast);
    border: 1px solid transparent;
}

.lang-btn:hover {
    background: var(--color-bg-card);
    color: var(--color-text-primary);
    transform: translateY(-1px);
}

.lang-btn.active {
    background: var(--gradient-quantum);
    color: white;
    border: 1px solid rgba(102, 126, 234, 0.3);
    box-shadow: var(--shadow-quantum);
}

/* Hero Section */
.hero {
    background: var(--gradient-hero);
    padding: var(--spacing-3xl) 0;
    text-align: center;
}

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

.hero-title {
    font-size: 3rem;
    font-weight: 800;
    margin-bottom: var(--spacing-lg);
    background: var(--gradient-quantum);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.hero-subtitle {
    font-size: 1.25rem;
    color: var(--color-text-secondary);
    margin-bottom: var(--spacing-2xl);
    line-height: 1.8;
}

.hero-features {
    display: flex;
    flex-wrap: wrap;
    gap: var(--spacing-md);
    justify-content: center;
}

.feature-pill {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    background: var(--color-bg-card);
    padding: var(--spacing-sm) var(--spacing-lg);
    border-radius: var(--radius-xl);
    border: 1px solid var(--color-bg-elevated);
    font-size: 0.875rem;
    font-weight: 500;
    transition: all var(--transition-base);
}

.feature-pill:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
    border-color: var(--color-primary);
}

.feature-icon {
    font-size: 1.25rem;
}

/* Main */
.main {
    flex: 1;
    padding: var(--spacing-3xl) 0;
}

/* Section Headers */
.section-header {
    text-align: center;
    margin-bottom: var(--spacing-2xl);
}

.section-header h2 {
    margin-bottom: var(--spacing-md);
}

.section-divider {
    width: 60px;
    height: 4px;
    background: var(--gradient-quantum);
    margin: 0 auto var(--spacing-md);
    border-radius: var(--radius-sm);
}

.section-subtitle {
    color: var(--color-text-muted);
    font-size: 1.125rem;
}

/* About Section */
.about-section {
    margin-bottom: var(--spacing-3xl);
}

.about-content {
    max-width: 800px;
    margin: 0 auto;
    font-size: 1.125rem;
    line-height: 1.8;
}

.about-content p {
    margin-bottom: var(--spacing-lg);
}

/* Demos Grid */
.demos-section {
    margin-bottom: var(--spacing-3xl);
}

.demos-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
    gap: var(--spacing-xl);
    margin-top: var(--spacing-2xl);
}

.demo-card {
    background: var(--color-bg-card);
    border-radius: var(--radius-xl);
    padding: var(--spacing-xl);
    border: 1px solid var(--color-bg-elevated);
    display: flex;
    flex-direction: column;
    transition: all var(--transition-base);
    position: relative;
    overflow: hidden;
}

.demo-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: var(--gradient-card);
    opacity: 0;
    transition: opacity var(--transition-base);
    z-index: 0;
}

.demo-card:hover {
    transform: translateY(-8px);
    box-shadow: var(--shadow-xl);
    border-color: var(--color-primary);
}

.demo-card:hover::before {
    opacity: 1;
}

.demo-card > * {
    position: relative;
    z-index: 1;
}

.demo-icon {
    font-size: 3rem;
    margin-bottom: var(--spacing-lg);
}

.demo-content {
    flex: 1;
}

.demo-content h3 {
    margin-bottom: var(--spacing-md);
    font-size: 1.5rem;
}

.demo-description {
    color: var(--color-text-secondary);
    margin-bottom: var(--spacing-lg);
    font-size: 0.95rem;
    line-height: 1.7;
}

.demo-tags {
    display: flex;
    flex-wrap: wrap;
    gap: var(--spacing-sm);
    margin-bottom: var(--spacing-lg);
}

.tag {
    background: var(--color-bg-elevated);
    color: var(--color-text-secondary);
    padding: var(--spacing-xs) var(--spacing-sm);
    border-radius: var(--radius-sm);
    font-size: 0.75rem;
    font-weight: 600;
    font-family: var(--font-mono);
}

.demo-footer {
    margin-top: auto;
}

/* Tech Section */
.tech-section {
    margin-bottom: var(--spacing-3xl);
}

.tech-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(400px, 1fr));
    gap: var(--spacing-xl);
    margin-top: var(--spacing-2xl);
}

.tech-card {
    background: var(--color-bg-card);
    border-radius: var(--radius-lg);
    padding: var(--spacing-xl);
    border: 1px solid var(--color-bg-elevated);
}

.tech-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: var(--spacing-md);
}

.tech-header h3 {
    font-size: 2rem;
    background: var(--gradient-quantum);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.tech-badge {
    background: var(--color-bg-elevated);
    color: var(--color-text-secondary);
    padding: var(--spacing-xs) var(--spacing-md);
    border-radius: var(--radius-md);
    font-size: 0.75rem;
    font-weight: 600;
}

.tech-card h4 {
    margin-bottom: var(--spacing-md);
    color: var(--color-text-primary);
}

.tech-card p {
    margin-bottom: var(--spacing-lg);
}

.tech-card ul {
    list-style: none;
    padding: 0;
}

.tech-card li {
    padding: var(--spacing-sm) 0;
    color: var(--color-text-secondary);
    font-size: 0.95rem;
}

.tech-card li::before {
    content: "✓ ";
    color: var(--color-accent);
    font-weight: bold;
    margin-right: var(--spacing-sm);
}

/* Buttons */
.button {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-sm);
    padding: var(--spacing-md) var(--spacing-xl);
    border: none;
    border-radius: var(--radius-md);
    font-family: var(--font-sans);
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: all var(--transition-base);
    text-decoration: none;
    width: 100%;
}

.button-primary {
    background: var(--gradient-quantum);
    color: white;
    box-shadow: var(--shadow-md);
}

.button-primary:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
    filter: brightness(1.1);
}

.button-icon {
    font-size: 1.25rem;
    transition: transform var(--transition-base);
}

.button-primary:hover .button-icon {
    transform: translateX(4px);
}

/* Footer */
.footer {
    background: var(--color-bg-card);
    border-top: 1px solid var(--color-bg-elevated);
    padding: var(--spacing-xl) 0;
    text-align: center;
    margin-top: auto;
}

.footer p {
    margin-bottom: var(--spacing-sm);
}

.footer-tech {
    margin-top: var(--spacing-md);
    font-size: 0.875rem;
    color: var(--color-text-muted);
}

.footer-tech strong {
    color: var(--color-text-secondary);
}

/* ===================================
   Animations
   =================================== */
@keyframes pulse {
    0%, 100% { transform: scale(1); }
    50% { transform: scale(1.05); }
}

@keyframes glow {
    0%, 100% { box-shadow: 0 0 20px rgba(102, 126, 234, 0.3); }
    50% { box-shadow: 0 0 40px rgba(102, 126, 234, 0.6); }
}

/* ===================================
   Responsive Design
   =================================== */
@media (max-width: 1200px) {
    .tech-grid {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 768px) {
    .hero-title {
        font-size: 2rem;
    }

    .hero-subtitle {
        font-size: 1rem;
    }

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

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

    .logo h1 {
        font-size: 1.5rem;
    }
}

@media (max-width: 480px) {
    .header {
        padding: var(--spacing-md) 0;
    }

    .header-content {
        flex-wrap: wrap;
        gap: var(--spacing-md);
    }

    .logo {
        gap: var(--spacing-sm);
        flex: 1;
        min-width: 0;
    }

    .logo h1 {
        font-size: 1.25rem;
    }

    .quantum-badge {
        font-size: 0.75rem;
        padding: var(--spacing-xs) var(--spacing-sm);
    }

    .language-switcher {
        flex-shrink: 0;
    }

    .lang-btn {
        font-size: 0.75rem;
        padding: 0.25rem 0.5rem;
    }

    .hero {
        padding: var(--spacing-2xl) 0;
    }

    .main {
        padding: var(--spacing-xl) 0;
    }

    .feature-pill {
        font-size: 0.75rem;
        padding: var(--spacing-xs) var(--spacing-md);
    }
}