iTIP: Override text color together with background color
This file sample.mbox contains the same information three times - as iCalendar, as HTML and as plain text. When I am in dark mode, and I tell evolution to “Show description provided by sender”, the text is displayed with white background on white foreground. Thus it cannot be read, unless the text is selected (then it can be read).
When Evolution (Gnome) is running in Light mode, then the text is properly displayed.
Considering that the HTML does not set any colours (except green/black for the title bar, which is displayed correctly), Evolution shall set for the background black, and keep white as default text-foreground in dark mode.