:root {
    --primary-color: #2c5e1a;
    --secondary-color: #8b5a2b;
    --background-color: #f4f7f6;
    --card-bg: #ffffff;
    --text-color: #333;
    --shadow: 0 4px 6px rgba(0,0,0,0.1);
}

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background-color: var(--background-color);
    color: var(--text-color);
    margin: 0;
    padding: 20px;
    display: flex;
    flex-direction: column;
    align-items: center;
}

header {
    text-align: center;
    margin-bottom: 40px;
}

h1 {
    color: var(--primary-color);
    font-size: 2.5rem;
}

.container {
    width: 100%;
    max-width: 1200px;
}

.categories {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 20px;
    margin-bottom: 50px;
}

.category-btn {
    background-color: var(--primary-color);
    color: white;
    padding: 30px;
    border-radius: 12px;
    text-align: center;
    text-decoration: none;
    font-size: 1.5rem;
    font-weight: bold;
    box-shadow: var(--shadow);
    transition: transform 0.2s, background-color 0.2s;
    cursor: pointer;
    border: none;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
}

.category-btn:hover {
    transform: translateY(-5px);
    background-color: #3d7a25;
}

.category-btn span {
    font-size: 0.9rem;
    font-weight: normal;
    margin-top: 10px;
    opacity: 0.9;
}

.materials-section {
    margin-top: 30px;
}

.materials-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 15px;
}

.material-card {
    background: var(--card-bg);
    padding: 20px;
    border-radius: 8px;
    box-shadow: var(--shadow);
    text-decoration: none;
    color: var(--text-color);
    border-left: 5px solid var(--secondary-color);
    transition: background-color 0.2s;
}

.material-card:hover {
    background-color: #f9f9f9;
}

.material-card h3 {
    margin: 0 0 5px 0;
    font-size: 1.2rem;
    color: var(--primary-color);
}

.material-card p {
    margin: 0;
    font-size: 0.9rem;
    color: #666;
}

footer {
    margin-top: 50px;
    font-size: 0.8rem;
    color: #888;
}

@media (max-width: 600px) {
    .category-btn {
        padding: 20px;
        font-size: 1.2rem;
    }
}