In order to change the background-color I did the following:
since the call is in layout.less
background: @xwiki-page-header-bg-color @xwiki-page-header-bg-image @xwiki-page-header-bg-position;
and since in variableInit.vm we have
if you want to have another color you will need to add in @lesscode something like:
in order to overwrite the skin.
I don't know what the problem is, since the preview is ok.