body {
    font-family: Arial, sans-serif;
    margin: 0;
    padding: 0;
    background-color: #0a0f2c;
    color: #ffffff;
}
header {
    background-color: #0c1c3d;
    padding: 20px;
    text-align: center;
}
nav {
    margin-top: 10px;
}
nav button {
    margin: 0 5px;
    padding: 10px 15px;
    background-color: #00c9a7;
    color: #fff;
    border: none;
    cursor: pointer;
    border-radius: 4px;
}
section {
    display: none;
    padding: 20px;
}
section.active {
    display: block;
}
footer {
    background-color: #0c1c3d;
    padding: 20px;
    text-align: center;
}