:root {
    --primary-color: #3776ab;
    --secondary-color: #ffd43b;
    --text-color: #333;
    --bg-color: #f5f5f5;
    --card-bg: #ffffff;
    --success-color: #4caf50;
    --warning-color: #ff9800;
}

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

body {
    font-family: "Segoe UI", Tahoma, Geneva, Verdana, sans-serif;
    line-height: 1.6;
    color: var(--text-color);
    background-color: var(--bg-color);
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
}

header {
    background: linear-gradient(
        135deg,
        var(--primary-color),
        var(--secondary-color)
    );
    color: white;
    padding: 2rem 0;
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
}

header h1 {
    font-size: 2.5rem;
    margin-bottom: 0.5rem;
}

header p {
    font-size: 1.2rem;
    opacity: 0.9;
}

nav {
    background: var(--card-bg);
    padding: 1rem 0;
    box-shadow: 0 2px 5px rgba(0, 0, 0, 0.1);
    position: sticky;
    top: 0;
    z-index: 100;
}

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

nav a {
    color: var(--primary-color);
    text-decoration: none;
    font-weight: 500;
    transition: color 0.3s;
}

nav a:hover,
nav a.active {
    color: var(--secondary-color);
}

main {
    padding: 2rem 0;
}

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

.course-card {
    background: var(--card-bg);
    border-radius: 10px;
    padding: 1.5rem;
    box-shadow: 0 3px 10px rgba(0, 0, 0, 0.1);
    transition:
        transform 0.3s,
        box-shadow 0.3s;
}

.course-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 5px 20px rgba(0, 0, 0, 0.15);
}

.course-card h3 {
    color: var(--primary-color);
    margin-bottom: 1rem;
}

.course-card .badge {
    display: inline-block;
    padding: 0.3rem 0.8rem;
    border-radius: 15px;
    font-size: 0.85rem;
    margin: 0.5rem 0;
}

.badge.beginner {
    background: var(--success-color);
    color: white;
}

.badge.intermediate {
    background: var(--warning-color);
    color: white;
}

.btn {
    display: inline-block;
    padding: 0.8rem 1.5rem;
    background: var(--primary-color);
    color: white;
    text-decoration: none;
    border-radius: 5px;
    transition: background 0.3s;
    margin-top: 1rem;
}

.btn:hover {
    background: #2c5f8d;
}

.content-section {
    background: var(--card-bg);
    border-radius: 10px;
    padding: 2rem;
    margin-bottom: 2rem;
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
}

.content-section h2 {
    color: var(--primary-color);
    margin-bottom: 1rem;
    border-bottom: 3px solid var(--secondary-color);
    padding-bottom: 0.5rem;
}

.step {
    margin: 1.5rem 0;
    padding-left: 1.5rem;
    border-left: 3px solid var(--secondary-color);
}

.step h3 {
    color: var(--primary-color);
    margin-bottom: 0.5rem;
}

pre {
    background: #2d2d2d;
    color: #f8f8f2;
    padding: 1rem;
    border-radius: 5px;
    overflow-x: auto;
    margin: 1rem 0;
}

code {
    background: #f0f0f0;
    padding: 0.2rem 0.4rem;
    border-radius: 3px;
    font-family: "Consolas", "Monaco", monospace;
}

pre code {
    background: none;
    padding: 0;
}

.highlight-box {
    background: #fffbeb;
    border-left: 4px solid var(--warning-color);
    padding: 1rem;
    margin: 1rem 0;
    border-radius: 5px;
}

.success-box {
    background: #e8f5e9;
    border-left: 4px solid var(--success-color);
    padding: 1rem;
    margin: 1rem 0;
    border-radius: 5px;
}

.code-reference {
    display: inline-block;
    padding: 0.5rem 1rem;
    background: var(--primary-color);
    color: white;
    text-decoration: none;
    border-radius: 5px;
    margin: 0.5rem 0;
    font-family: monospace;
}

.code-reference:hover {
    background: #2c5f8d;
}

footer {
    background: var(--text-color);
    color: white;
    text-align: center;
    padding: 2rem 0;
    margin-top: 3rem;
}

.progress-indicator {
    display: flex;
    justify-content: space-between;
    margin: 2rem 0;
    padding: 1rem;
    background: var(--card-bg);
    border-radius: 10px;
}

.progress-step {
    flex: 1;
    text-align: center;
    padding: 0.5rem;
    position: relative;
}

.progress-step.completed {
    color: var(--success-color);
}

.progress-step.current {
    color: var(--primary-color);
    font-weight: bold;
}

.image-gallery {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 1rem;
    margin: 1rem 0;
}

.image-gallery img {
    width: 100%;
    border-radius: 5px;
    box-shadow: 0 2px 5px rgba(0, 0, 0, 0.1);
}

.info-expandable {
    margin: 1rem 0;
    border: 1px solid #ddd;
    border-radius: 5px;
    overflow: hidden;
}

.info-expandable summary {
    background: #f8f9fa;
    padding: 0.75rem 1rem;
    cursor: pointer;
    font-weight: 500;
    color: var(--primary-color);
    user-select: none;
    transition: background 0.2s;
}

.info-expandable summary:hover {
    background: #e9ecef;
}

.info-expandable summary::marker {
    content: "▶ ";
}

.info-expandable[open] summary::marker {
    content: "▼ ";
}

.info-expandable-content {
    padding: 1rem;
    background: #fafbfc;
}

@media (max-width: 768px) {
    header h1 {
        font-size: 1.8rem;
    }

    nav ul {
        flex-direction: column;
        gap: 0.5rem;
    }

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