Qt Creator Offline Help and Qt Assistant may end up hardly readable with some desktop color schemes

This issue impacts both Qt Creator's "Offline Help" panel/window and the Qt Assistant tool itself. Similarly to QTCREATORBUG-1853, some desktop color schemes, such as KDE's "Obsidian Coast", make help pages hardly readable (see attached screenshot). I guess this is due to the background color not being forced according to foreground colors.

Note: this can of course be circumvented using Qt stylesheets:

HelpViewer { background-color: white; } 
QWebView { background-color: white; }

qtcreator -stylesheet ~/assistant-stylesheet.css
assistant -stylesheet ~/assistant-stylesheet.css