/* Main CSS for Web Development Learning Hub */

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

/* Base Styles */
:root {
    --primary-color: #4a6fa5;
    --secondary-color: #166088;
    --accent-color: #47b8e0;
    --text-color: #333;
    --light-bg: #f5f7fa;
    --dark-bg: #2c3e50;
    --card-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
    --transition: all 0.3s ease;
    --border-radius: 8px;
}

html {
    font-size: 62.5%; /* 10px = 1rem */
    scroll-behavior: smooth;
}

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    font-size: 1.6rem;
    line-height: 1.6;
    color: var(--text-color);
    background-color: var(--light-bg);
    max-width: 1200px;
    margin: 0 auto;
    padding: 2rem;
}

/* Typography */
h1, h2, h3, h4, h5, h6 {
    margin-bottom: 1.5rem;
    font-weight: 700;
    line-height: 1.2;
    color: var(--primary-color);
}

h1 {
    font-size: 3.6rem;
    margin-top: 2rem;
    text-align: center;
}

h2 {
    font-size: 2.8rem;
    margin-top: 4rem;
    padding-bottom: 0.5rem;
    border-bottom: 2px solid var(--accent-color);
}

h3 {
    font-size: 2.4rem;
    margin-top: 3rem;
    color: var(--secondary-color);
}

p {
    margin-bottom: 1.5rem;
}

a {
    color: var(--secondary-color);
    text-decoration: none;
    transition: var(--transition);
}

a:hover {
    color: var(--accent-color);
    text-decoration: underline;
}

/* Layout Components */
header {
    text-align: center;
    padding: 4rem 2rem;
    background-color: white;
    border-radius: var(--border-radius);
    box-shadow: var(--card-shadow);
    margin-bottom: 3rem;
}

header p {
    font-size: 1.8rem;
    color: #666;
    max-width: 800px;
    margin: 0 auto;
}

nav {
    background-color: var(--dark-bg);
    border-radius: var(--border-radius);
    margin-bottom: 3rem;
    padding: 1rem;
}

nav ul {
    list-style: none;
    display: flex;
    justify-content: center;
    gap: 2rem;
}

nav li {
    margin: 0;
}

nav a {
    display: block;
    padding: 1rem 2rem;
    color: white;
    font-weight: bold;
    border-radius: var(--border-radius);
    transition: var(--transition);
}

nav a:hover {
    background-color: var(--accent-color);
    color: white;
    text-decoration: none;
}

main {
    background-color: white;
    border-radius: var(--border-radius);
    box-shadow: var(--card-shadow);
    padding: 3rem;
}

.learning-section {
    margin-bottom: 5rem;
    padding-bottom: 3rem;
    border-bottom: 1px solid #eee;
}

.learning-section:last-child {
    border-bottom: none;
    margin-bottom: 0;
}

.level-cards {
    display: flex;
    flex-wrap: wrap;
    gap: 2rem;
    margin: 3rem 0;
}

.card {
    flex: 1 1 300px;
    background-color: var(--light-bg);
    border-radius: var(--border-radius);
    padding: 2rem;
    box-shadow: var(--card-shadow);
    transition: var(--transition);
}

.card:hover {
    transform: translateY(-5px);
    box-shadow: 0 8px 15px rgba(0, 0, 0, 0.1);
}

.btn {
    display: inline-block;
    background-color: var(--primary-color);
    color: white;
    padding: 1rem 2rem;
    border-radius: var(--border-radius);
    margin-top: 1.5rem;
    font-weight: bold;
    transition: var(--transition);
}

.btn:hover {
    background-color: var(--secondary-color);
    text-decoration: none;
    color: white;
}

.comprehensive-link {
    display: block;
    text-align: center;
    margin-top: 2rem;
    font-weight: bold;
    font-size: 1.8rem;
}

footer {
    text-align: center;
    margin-top: 4rem;
    padding: 2rem;
    color: #666;
    font-size: 1.4rem;
}

/* Responsive Design */
@media (max-width: 768px) {
    body {
        padding: 1rem;
    }
    
    .level-cards {
        flex-direction: column;
    }
    
    h1 {
        font-size: 3rem;
    }
    
    h2 {
        font-size: 2.4rem;
    }
    
    h3 {
        font-size: 2rem;
    }
    
    nav ul {
        flex-direction: column;
        align-items: center;
    }
}

@media (max-width: 480px) {
    html {
        font-size: 55%;
    }
    
    header, main {
        padding: 1.5rem;
    }
}

/* Animation */
@keyframes fadeIn {
    from { opacity: 0; transform: translateY(20px); }
    to { opacity: 1; transform: translateY(0); }
}

.learning-section {
    animation: fadeIn 0.5s ease-out;
}

.card:nth-child(1) { animation-delay: 0.1s; }
.card:nth-child(2) { animation-delay: 0.2s; }
.card:nth-child(3) { animation-delay: 0.3s; }