html, body{
    padding: 0;
    margin: 0;
    width: 100%;
    height: 100%;
}
a{
    display: block;
    width: 100%;
    height: 100vh;
    background: url(thisistheend.jpg) no-repeat;
    background-size: 100% 100%;
    cursor: pointer;
}
@media screen and (max-width: 980px){
    a{
        background-size: contain;
    }
}