For me the light/bright colors are really straining my eyes since they're very sensitive to glare/bright lights as a consequence of cataracts.

Also the switching of the FG and BG colors was just an example I could think of in the moment to get something like "dark mode" with minimal effort. In practice I'd probably go with a somewhat "off-white"(?) FG on a medium-dark grey BG. IMO a less bright white text color in this scenario does well in eliminating the "shrinking" you speak of while the contrast with the muted grey BG isn't too harsh.