Hello, do I need to change URL to SRC or IMG to get my BG swap images to display in Litmus? I could host them and place a valid url but that isn't how it's going to be deployed so I'm trying to get email to display as is but when I upload the direct files it still won't show the background image swaps even though the assets are all uploaded.

thanks in advance for the help,

body .imgSwap03AFeature {

    width: 320px !important;
    height: 280px !important;
    background-image:url("freeship_mobile.jpg");
    background-size: 320px 280px !important;
    display:block;
}