:root {
    --bg-color: #0f172a;
    --card-bg: #1e293b;
    --text-primary: #f8fafc;
    --text-secondary: #94a3b8;
    --accent-color: #38bdf8;
    --accent-gradient: linear-gradient(135deg, #38bdf8 0%, #818cf8 100%);
    --border-color: #334155;
    --font-family: 'Inter', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
    --container-width: 800px;
}

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

body {
    background-color: var(--bg-color);
    color: var(--text-primary);
    font-family: var(--font-family);
    line-height: 1.6;
    -webkit-font-smoothing: antialiased;
}

.container {
    max-width: var(--container-width);
    margin: 0 auto;
    padding: 2rem;
}

/* Header */
header {
    margin-bottom: 4rem;
    text-align: center;
    padding-top: 2rem;
}

h1 {
    font-size: 2.5rem;
    font-weight: 800;
    margin-bottom: 1rem;
    background: var(--accent-gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    letter-spacing: -0.02em;
}

.subtitle {
    color: var(--text-secondary);
    font-size: 1.1rem;
}

/* Navigation */
nav {
    margin-bottom: 3rem;
    display: flex;
    justify-content: center;
    gap: 1.5rem;
}

nav a {
    color: var(--text-secondary);
    text-decoration: none;
    font-weight: 500;
    transition: color 0.2s ease;
    padding: 0.5rem 1rem;
    border-radius: 0.5rem;
}

nav a:hover, nav a.active {
    color: var(--text-primary);
    background-color: var(--card-bg);
}

/* Content */
.content-card {
    background-color: var(--card-bg);
    border: 1px solid var(--border-color);
    border-radius: 1rem;
    padding: 2.5rem;
    box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
}

h2 {
    font-size: 1.5rem;
    margin-top: 2rem;
    margin-bottom: 1rem;
    color: var(--text-primary);
}

h2:first-child {
    margin-top: 0;
}

h3 {
    font-size: 1.2rem;
    margin-top: 1.5rem;
    margin-bottom: 0.75rem;
    color: var(--text-primary);
}

p {
    margin-bottom: 1rem;
    color: var(--text-secondary);
}

ul {
    margin-bottom: 1rem;
    padding-left: 1.5rem;
    color: var(--text-secondary);
}

li {
    margin-bottom: 0.5rem;
}

a {
    color: var(--accent-color);
    text-decoration: none;
    transition: opacity 0.2s;
}

a:hover {
    opacity: 0.8;
}

/* Footer */
footer {
    margin-top: 4rem;
    text-align: center;
    color: var(--text-secondary);
    font-size: 0.9rem;
    padding-bottom: 2rem;
}

/* Responsive */
@media (max-width: 640px) {
    .container {
        padding: 1rem;
    }
    
    h1 {
        font-size: 2rem;
    }
    
    .content-card {
        padding: 1.5rem;
    }
}