Styles: Add force-style overrides for accessability

[Jowan-Spooner]

For accessability it would be very useful to be able to override certain settings of the styles, especially font, font_size, font_color & bg_color/modulation. This should also be doable from code so this can easily be made a setting.

It should be "relatively" easy to allow force-applying these additional style settings, just have to figure out the UI.