White background in dark mode for Matplotlib, Vim docsets

When I open a document in Zeal using this search query:

python,django,twisted,sphinx,flask,tornado,sqlalchemy,numpy,scipy,salt,pandas,matplotlib,cvp:set_ticks

I get redirected to a correct doc but the background is white instead of dark - this together with white font color (default in dark mode) causes, that the text is not visible (see below).

Note: this does not happen in other docsets (e.g. pandas)