Add a browser extension like
$1. It has settings to remove a lot of FB's extra crap, including bg colors and the enlarged text as well as emojis and changing the like buttons to text (e.g., "lik 2 lov haha 3"). Can also set custom foreground/background/link colors and font type and size.
I use it for way more, like newsfeed filtering and getting rid of lots of the sidebar spam, but it's got some nice accessibility features inadvertently built in.