Install button has bad contrast

[matthiasclasen]

The grey text on the green background does not have good contrast, and looks a bit out of place.

I would suggest to either make the text white, or stick to the default theme colors.

[matthiasclasen]

Oh, now I see that this was only for the welcome page, when the install button is disabled.

It does make the app look a bit unpolished on the first impression. Maybe the green should be toned down or just be a dark gray for the disabled state.

[nekohayo]

Alternatively, maybe all of that headerbar's buttons could be set to hidden state instead of disabled, when the app starts and until a font is selected from the sidebar.