body {
    margin: 0;
    font-family: Arial, sans-serif;
    background: url('fundo-guincho.jpg') no-repeat center center;
    background-size: cover;
    background-attachment: fixed;
}
header {
    background-color: red;
    padding: 10px;
    text-align: center;
}
.call-button {
    background-color: green;
    color: white;
    padding: 10px 15px;
    text-decoration: none;
    font-size: 18px;
    border-radius: 5px;
}
main {
    text-align: center;
    padding: 50px 20px;
    color: white;
    text-shadow: 1px 1px 2px black;
}
.whatsapp-button {
    position: fixed;
    bottom: 20px;
    right: 20px;
    background-color: green;
    color: white;
    padding: 15px 20px;
    text-decoration: none;
    border-radius: 50px;
    font-size: 16px;
    z-index: 999;
}
@media (max-width: 768px) {
    body {
        background-attachment: scroll;
        background-position: center top;
    }
    main {
        padding: 30px 10px;
    }
}