/* Base styles */
:root {
    --main-bg: linear-gradient(135deg, #667eea, #764ba2);
    --header-bg: linear-gradient(135deg, #2c3e50, #34495e);
    --card-bg: #ffffff;
    --text-light: #ffffff;
    --text-dark: #2c3e50;
    --primary: #667eea;
    --secondary: #764ba2;
    --shadow: 0 10px 20px rgba(0,0,0,0.1);
    --radius: 12px;
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
}

body {
    background: var(--main-bg);
    min-height: 100vh;
    padding: 20px;
    display: flex;
    justify-content: center;
    align-items: center;
}

.container {
    width: 100%;
    max-width: 1000px;
    background: var(--card-bg);
    border-radius: var(--radius);
    box-shadow: var(--shadow);
    overflow: hidden;
}

.header {
    background: var(--header-bg);
    color: var(--text-light);
    padding: 30px;
    text-align: center;
}

.header h1 {
    font-size: 2.2rem;
    margin-bottom: 10px;
    font-weight: 600;
}

.subtitle {
    font-size: 1.2rem;
    opacity: 0.9;
}

.course-selection {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 25px;
    padding: 30px;
}

.course-card {
    background: var(--card-bg);
    border: 1px solid #e0e0e0;
    border-radius: var(--radius);
    padding: 25px;
    cursor: pointer;
    transition: all 0.3s ease;
    box-shadow: 0 4px 6px rgba(0,0,0,0.05);
}

.course-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 10px 20px rgba(0,0,0,0.1);
    border-color: var(--primary);
}

.course-card h2 {
    color: var(--primary);
    margin-bottom: 10px;
    font-size: 1.5rem;
}

.course-card p {
    color: #666;
    line-height: 1.5;
}

@media (max-width: 768px) {
    .course-selection {
        grid-template-columns: 1fr;
        padding: 20px;
    }
    
    .header {
        padding: 20px;
    }
    
    .header h1 {
        font-size: 1.8rem;
    }
}