Does not parse image urls in css like background: url('img/url.png');

[PeterNerlich]

I am trying to make a comic epub out of scanned pages. To make sure the image covers the whole page i tested the following code as chapter data:

<div style="
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background-repeat: no-repeat;
    background-position: center;
    background-size: contain;
    background-image: url(file://inserting/my/file.here);
">
</div>

This however does only work since the file is fetched from the same location by the eBook reader, a quick look into the code reveals that the URL has not been changed and the file was not added.