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

body {
    font-family: Arial, Helvetica, sans-serif;
    background-color: #f2f4f7;
    color: #222;
    line-height: 1.6;
}

main {
    max-width: 1100px;
    margin: 1.5rem auto 2rem;
    padding: 0 1rem;
}

.intro {
    margin-bottom: 1.5rem;
}

.intro h2 {
    margin-bottom: 0.5rem;
}

.features {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 1rem;
    margin-bottom: 2rem;
}

.feature-box {
    background-color: #ffffff;
    border-radius: 6px;
    padding: 1rem;
    border: 1px solid #d0d4dc;
    box-shadow: 0 2px 4px rgba(0, 0, 0, 0.06);
}

.feature-box h3 {
    margin-bottom: 0.5rem;
    color: #0b4c8c; 
}

.class-link {
    background-color: #ffffff;
    border-radius: 6px;
    padding: 1rem;
    border: 1px solid #d0d4dc;
}

.class-link a {
    color: #0b4c8c;
    text-decoration: none;
    font-weight: bold;
}

.class-link a:hover {
    text-decoration: underline;
}

.site-footer {
    background-color: #111111;
    color: #f2f4f7;
    text-align: center;
    padding: 0.75rem 0.5rem;
}


.main-nav ul {
    list-style: none;
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
}

.main-nav a {
    display: block;
    padding: 0.5rem 0.9rem;
    text-decoration: none;
    color: #f2f4f7;
    background-color: #1f2933; 
    border-radius: 4px;
    font-size: 0.95rem;
}

.main-nav a:hover,
.main-nav a.active {
    background-color: #0b4c8c; 
}


@media (max-width: 800px) {
    .features {
        grid-template-columns: 1fr 1fr;
    }
}

@media (max-width: 550px) {
    .features {
        grid-template-columns: 1fr;
    }

    main {
        padding: 0 0.75rem;
    }
}