body {
    font-family: Arial, sans-serif;
    background-color: #111;
    color: #eee;
    margin: 0;
    padding: 0;
}
header {
    background-color: #000;
    padding: 10px;
    display: flex;
    align-items: center;
    justify-content: space-between;
}
.logo {
    height: 50px;
}
nav a {
    color: #00aaff;
    margin: 0 10px;
    text-decoration: none;
}
main {
    padding: 20px;
}
form {
    margin-top: 20px;
}
input, button {
    padding: 10px;
    margin: 5px 0;
    width: 100%;
    max-width: 300px;
}
.whatsapp-knop {
    display: inline-block;
    margin-top: 20px;
    padding: 10px;
    background-color: #25d366;
    color: #fff;
    text-decoration: none;
    border-radius: 5px;
}
footer {
    background-color: #000;
    color: #aaa;
    text-align: center;
    padding: 10px;
}