body {
    background-image: url('../img/background.png');
    background-position: center;
    background-attachment: fixed;
    background-size: 100% 100%;
    overflow-x: hidden;
}

html {
    height: 100%;
    margin: 0;
    padding: 0;
    overflow-x: hidden;
}

@media (max-width: 640px) {
    body {
        background-image: url('../img/bg_vertical.png');
        padding-top: 8px; 
    }
}