I don't think this is correct: What I implemented in symfony/symfony#45376 is only support for the old-timey background="" attribute, not for CSS background-image (see also the PR description). It could be added realtively easily and it would certainly be nice to have, but it's not implemented as of now

@flack thanks for telling me about this error. I've fixed it in b39f0de Cheers!

@javiereguiluz sorry, but that's still not right. What I implemented was only support for this:

<div background="cid:some-img.png"></div>

So really the HTML attribute background, not the CSS property by the same name

@flack fixed again! Thanks.

See 868e311