Style not displayed correctly on phpBB Demo site

Released styles get a demo page on this site, e.g.: https://www.phpbb.com/customise/db/styl ... l/demo/3.1 which works as intended.

The phpBB 3.2.x versions of that style changed the way that the header image is rendered, it is no longer defined in the .css, but is defined directly in the html (which makes the behaviour of elements surrounding the image in responsive modes a little more predictable). The problem is that in the demo, the header image is now not loaded at all: https://www.phpbb.com/customise/db/styl ... l/demo/3.2

I presume that these demos are generated with something that is not standard phpBB, but wonder what could be done to fix this?