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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, sans-serif;
    background: #f5f5f5;
    color: #333;
    line-height: 1.6;
}

header {
    background: linear-gradient(135deg, #1e3c72 0%, #2a5298 100%);
    color: white;
    padding: 4rem 2rem;
    text-align: center;
}

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

header p {
    font-size: 1.25rem;
    opacity: 0.9;
    max-width: 600px;
    margin: 0 auto;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 3rem 2rem;
}

.section {
    margin-bottom: 4rem;
}

.section-title {
    font-size: 2rem;
    color: #1e3c72;
    margin-bottom: 2rem;
    text-align: center;
    position: relative;
}

.section-title::after {
    content: '';
    display: block;
    width: 60px;
    height: 4px;
    background: #2a5298;
    margin: 0.5rem auto 0;
    border-radius: 2px;
}

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

.card {
    background: white;
    border-radius: 12px;
    overflow: hidden;
    box-shadow: 0 4px 20px rgba(0, 0, 0, 0.08);
    transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.card:hover {
    transform: translateY(-8px);
    box-shadow: 0 12px 40px rgba(0, 0, 0, 0.12);
}

.card-image {
    width: 100%;
    height: 220px;
    object-fit: cover;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
}

.card-content {
    padding: 1.5rem;
}

.card-tag {
    display: inline-block;
    background: #e8f0fe;
    color: #2a5298;
    padding: 0.25rem 0.75rem;
    border-radius: 20px;
    font-size: 0.8rem;
    font-weight: 600;
    margin-bottom: 0.75rem;
}

.card h3 {
    font-size: 1.25rem;
    color: #1e3c72;
    margin-bottom: 0.75rem;
}

.card p {
    color: #666;
    font-size: 0.95rem;
}

.tech-stack {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
    margin-top: 1rem;
}

.tech-tag {
    background: #f0f4f8;
    color: #4a5568;
    padding: 0.25rem 0.75rem;
    border-radius: 16px;
    font-size: 0.75rem;
    font-weight: 500;
}

footer {
    background: #1a2a4a;
    color: white;
    text-align: center;
    padding: 2rem;
}

nav {
    background: white;
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.05);
    position: sticky;
    top: 0;
    z-index: 100;
}

.nav-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 1rem 2rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.nav-logo {
    font-size: 1.25rem;
    font-weight: 700;
    color: #1e3c72;
    text-decoration: none;
}

.nav-links {
    display: flex;
    gap: 2rem;
    list-style: none;
}

.nav-links a {
    color: #4a5568;
    text-decoration: none;
    font-weight: 500;
    transition: color 0.2s;
}

.nav-links a:hover,
.nav-links a.active {
    color: #2a5298;
}

.page-header {
    background: #f8fafc;
    padding: 3rem 2rem;
    text-align: center;
    border-bottom: 1px solid #e2e8f0;
}

.page-header h1 {
    font-size: 2.5rem;
    color: #1e3c72;
    margin-bottom: 0.5rem;
}

.page-header p {
    color: #64748b;
    font-size: 1.1rem;
}

.content {
    max-width: 800px;
    margin: 0 auto;
    padding: 3rem 2rem;
}

.content h2 {
    color: #1e3c72;
    margin: 2rem 0 1rem;
    font-size: 1.5rem;
}

.content h3 {
    color: #2a5298;
    margin: 1.5rem 0 0.75rem;
    font-size: 1.2rem;
}

.content p {
    margin-bottom: 1rem;
    color: #4a5568;
}

.content ul {
    margin: 1rem 0 1rem 1.5rem;
}

.content li {
    margin-bottom: 0.5rem;
    color: #4a5568;
}

.content a {
    color: #2a5298;
    text-decoration: none;
}

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

.error-page {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    min-height: 60vh;
    text-align: center;
    padding: 2rem;
}

.error-code {
    font-size: 8rem;
    font-weight: 700;
    color: #e2e8f0;
    line-height: 1;
    margin-bottom: 1rem;
}

.error-message {
    font-size: 1.5rem;
    color: #64748b;
    margin-bottom: 2rem;
}

.btn {
    display: inline-block;
    background: #2a5298;
    color: white;
    padding: 0.75rem 2rem;
    border-radius: 8px;
    text-decoration: none;
    font-weight: 600;
    transition: background 0.2s;
}

.btn:hover {
    background: #1e3c72;
}

@media (max-width: 768px) {
    header h1 {
        font-size: 2rem;
    }
    
    .section-title {
        font-size: 1.5rem;
    }
    
    .nav-links {
        gap: 1rem;
    }
    
    .error-code {
        font-size: 5rem;
    }
}