body {
    font-family: 'Roboto', Arial, sans-serif;
    margin: 0;
    background-color: #f4f4f9;
    color: #333;
    line-height: 1.6;
}

main {
    margin: 50px;
}

header {
    background-color: #292b2f;
    color: #fff;
    padding: 10px 20px;
    position: sticky;
    top: 0;
    z-index: 1000;
    box-shadow: 0px 4px 6px rgba(0, 0, 0, 0.1);
}

header nav {
    display: flex;
    justify-content: center;
    align-items: center;
}

header nav ul {
    list-style: none;
    display: flex;
    gap: 20px;
}

header nav ul li a {
    color: #fff;
    text-decoration: none;
    font-weight: bold;
    padding: 5px 10px;
    transition: background-color 0.3s, color 0.3s;
}

header nav ul li a:hover,
header nav ul li a.active {
    background-color: #ff9900;
    color: #292b2f;
    border-radius: 5px;
}

footer {
    background-color: #292b2f;
    color: #fff;
    padding: 10px 20px;
    text-align: center;
    font-size: 0.9em;
}

@media (max-width: 768px) {
    header nav ul {
        flex-direction: column;
        gap: 10px;
    }

    main section {
        flex-direction: column;
    }

    main article {
        max-width: 100%;
    }
}