body {
    font-family: Arial, sans-serif;
    margin: 0;
    background: #f4f4f4;
}

header {
    background: #0074D9;
    color: white;
    padding: 1em;
    text-align: center;
}

nav button {
    margin: 0.5em;
    padding: 0.5em 1em;
    background: white;
    color: #0074D9;
    border: none;
    cursor: pointer;
    border-radius: 5px;
}

nav button:hover {
    background: #005fa3;
    color: white;
}

main {
    padding: 1em;
}

section {
    display: none;
    background: white;
    padding: 1em;
    border-radius: 8px;
    margin-top: 1em;
}

section.active {
    display: block;
}

footer {
    background: #333;
    color: white;
    text-align: center;
    padding: 0.5em;
    position: fixed;
    width: 100%;
    bottom: 0;
}