Thanks, I just found a small bug. The font sizes should work again if you download the latest version. The mobile font sizes are still driven by the Minimal Theme Settings but slightly adjusted to compensate for screen sizes.
Bluefire Reader offers plenty of cool features. You can bookmark, annotate, highlight, share experts and search definitions with just a tap. Plus, you can switch between day and night themes, as well as customize the font and size of the layout.