body.dark-theme {
    background-color: #111;
    color: #eee;
    font-family: 'Segoe UI', sans-serif;
    margin: 0;
    padding: 0;
}
header, footer {
    background-color: #1a1a1a;
    padding: 1em;
    text-align: center;
}
nav ul {
    list-style: none;
    padding: 0;
}
nav ul li {
    display: inline;
    margin: 0 1em;
}
a {
    color: #62dafc;
    text-decoration: none;
}
.btn {
    display: inline-block;
    padding: 0.5em 1em;
    background-color: #62dafc;
    color: #111;
    text-decoration: none;
    border-radius: 4px;
}