body {
    /* a useless comment */
    background: url("image1.png");
    font: 1em;
    background: url("image2.png");
    background: blue;
}


#main1 {
    /* a useless comment */
    background-image: url("image3.png") ;
}


#main2 {
    background: transparent url("image1.png") no-repeat center center, transparent url(data:image/gif;base64,R0lGODlhEAAQAMQAAORHHOVSKud) no-repeat center center, transparent url("image3.png") no-repeat center center;
}

#main3 {
    background-image: url("image1.png")
}
#main4 {
    background-image: url(data:image/gif;base64,R0lGODlhEAAQAMQAAORHHOVSKud);
}
@media (min-width: 400px) {
    #application {
        width: 400px;
        margin: 0 auto;
        background-image: url(data:image/gif;base64,R0lGODlhEAAQAMQAAORHHOVSKud);
    }
}