body {
    font-family: Arial, sans-serif;
    background: #f7f7f7;
    margin: 0;
    padding: 0;
    text-align: center;
}
header {
    background: #222;
    color: white;
    padding: 20px;
}
h1 {
    margin: 0;
    font-size: 28px;
}
p {
    font-size: 18px;
    margin-top: 10px;
}
.btn {
    display: inline-block;
    margin-top: 20px;
    padding: 12px 20px;
    background: #25D366;
    color: white;
    text-decoration: none;
    font-size: 18px;
    border-radius: 6px;
}
footer {
    margin-top: 40px;
    padding: 20px;
    font-size: 14px;
    color: #555;
}