/* ===================================
   Global Styles
   =================================== */

:root {
    /* Color Palette */
    --primary-color: #2563eb;
    --primary-dark: #1e40af;
    --secondary-color: #7c3aed;
    --accent-color: #f59e0b;
    --success-color: #10b981;
    --bg-color: #0f172a;
    --bg-light: #1e293b;
    --bg-lighter: #334155;
    --text-color: #e2e8f0;
    --text-muted: #94a3b8;
    --border-color: #475569;

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

    /* Typography */
    --font-body: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
    --font-mono: 'Fira Code', 'Courier New', monospace;
}

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

body {
    font-family: var(--font-body);
    background: linear-gradient(135deg, var(--bg-color) 0%, #1a1f35 100%);
    color: var(--text-color);
    line-height: 1.6;
    min-height: 100vh;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--spacing-md);
}

/* ===================================
   Header
   =================================== */

header {
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--secondary-color) 100%);
    padding: var(--spacing-xl) 0;
    text-align: center;
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.3);
}

header h1 {
    font-size: 2.5rem;
    font-weight: 700;
    margin-bottom: var(--spacing-sm);
    text-shadow: 2px 2px 4px rgba(0, 0, 0, 0.3);
}

.subtitle {
    font-size: 1.2rem;
    opacity: 0.95;
    margin-bottom: var(--spacing-xs);
}

.author {
    font-size: 0.95rem;
    opacity: 0.85;
    font-style: italic;
}

/* ===================================
   Main Content
   =================================== */

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

section {
    margin-bottom: var(--spacing-xl);
}

h2 {
    font-size: 2rem;
    margin-bottom: var(--spacing-md);
    color: var(--primary-color);
    border-bottom: 2px solid var(--border-color);
    padding-bottom: var(--spacing-sm);
}

/* ===================================
   Introduction Section
   =================================== */

.intro {
    background: var(--bg-light);
    padding: var(--spacing-lg);
    border-radius: 12px;
    border-left: 4px solid var(--primary-color);
}

.intro p {
    font-size: 1.1rem;
    line-height: 1.8;
    color: var(--text-muted);
    margin-bottom: var(--spacing-md);
}

.tech-stack {
    display: flex;
    gap: var(--spacing-sm);
    flex-wrap: wrap;
}

.tech-badge {
    background: var(--primary-dark);
    padding: var(--spacing-xs) var(--spacing-md);
    border-radius: 20px;
    font-size: 0.9rem;
    font-weight: 500;
}

/* ===================================
   Algorithm Grid
   =================================== */

.algorithm-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
    gap: var(--spacing-lg);
    margin-top: var(--spacing-lg);
}

.algorithm-card {
    background: var(--bg-light);
    border: 1px solid var(--border-color);
    border-radius: 12px;
    padding: var(--spacing-lg);
    transition: all 0.3s ease;
    position: relative;
    overflow: hidden;
}

.algorithm-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 4px;
    background: linear-gradient(90deg, var(--primary-color), var(--secondary-color));
    transform: scaleX(0);
    transform-origin: left;
    transition: transform 0.3s ease;
}

.algorithm-card:hover::before {
    transform: scaleX(1);
}

.algorithm-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 10px 30px rgba(37, 99, 235, 0.3);
    border-color: var(--primary-color);
}

.algorithm-card.coming-soon {
    opacity: 0.6;
}

.algorithm-card.coming-soon:hover {
    transform: none;
    box-shadow: none;
}

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

.card-header h3 {
    font-size: 1.4rem;
    color: var(--text-color);
    margin: 0;
}

.badge {
    background: var(--success-color);
    color: white;
    padding: 0.25rem 0.75rem;
    border-radius: 12px;
    font-size: 0.75rem;
    font-weight: 600;
    text-transform: uppercase;
}

.badge.soon {
    background: var(--text-muted);
}

.card-description {
    color: var(--text-muted);
    line-height: 1.6;
    margin-bottom: var(--spacing-md);
}

.card-topics {
    display: flex;
    gap: var(--spacing-xs);
    flex-wrap: wrap;
    margin-bottom: var(--spacing-md);
}

.topic {
    background: var(--bg-lighter);
    padding: 0.25rem 0.75rem;
    border-radius: 6px;
    font-size: 0.85rem;
    color: var(--accent-color);
}

.card-link {
    display: inline-block;
    color: var(--primary-color);
    text-decoration: none;
    font-weight: 600;
    transition: all 0.3s ease;
    position: relative;
}

.card-link::after {
    content: '';
    position: absolute;
    bottom: -2px;
    left: 0;
    width: 0;
    height: 2px;
    background: var(--primary-color);
    transition: width 0.3s ease;
}

.card-link:hover::after {
    width: 100%;
}

.card-link:hover {
    color: var(--secondary-color);
}

/* ===================================
   Learning Philosophy Section
   =================================== */

.philosophy-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: var(--spacing-md);
    margin-top: var(--spacing-lg);
}

.philosophy-item {
    background: var(--bg-light);
    padding: var(--spacing-lg);
    border-radius: 12px;
    border-left: 3px solid var(--accent-color);
}

.philosophy-item h3 {
    font-size: 1.2rem;
    margin-bottom: var(--spacing-sm);
    color: var(--text-color);
}

.philosophy-item p {
    color: var(--text-muted);
    font-size: 0.95rem;
}

/* ===================================
   Footer
   =================================== */

footer {
    background: var(--bg-light);
    padding: var(--spacing-lg) 0;
    text-align: center;
    border-top: 1px solid var(--border-color);
    margin-top: var(--spacing-xl);
}

footer p {
    color: var(--text-muted);
    margin-bottom: var(--spacing-xs);
}

footer a {
    color: var(--primary-color);
    text-decoration: none;
    transition: color 0.3s ease;
}

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

.footer-note {
    font-size: 0.9rem;
    font-style: italic;
}

/* ===================================
   Responsive Design
   =================================== */

@media (max-width: 768px) {
    header h1 {
        font-size: 2rem;
    }

    .subtitle {
        font-size: 1rem;
    }

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

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