body{
        background-image:url('https://www.clubdock.cz/wp-content/uploads/2021/11/Web_back.jpg');
        background-repeat:no-repeat;
        background-size:cover;
        -webkit-background-size:cover;
        -moz-background-size:cover;
        -o-background-size:cover;
        background-attachment:fixed;
        background-position:center center;
    }