My problem is the opposite of yours. I want Konqueror to use the Website's font settings, specially the colors.
Here's what I observed:
- when displaying web pages, Konqueror uses the font settings in KControl > Appearance & Themes. Meaning, the fonts it uses are the ones used by the syste.
- when acting as a file manager, Konqueror uses the font settings in Settings > Configure Konqueror > Appearance.
I'm not absolutely sure about this, though. It's only based on my observation.