When this all started I had to start highlighting the paragraph I was reading to get through it, now some sites have blocked the ability to highlight and others don't use standard colors for it.
This isn't a fool-proof fix, but I would encourage you to try using Stylish extension (Chrome version, Firefox version, Opera version). You can find a global-scope styles that change every website you visit (here is one of my favourite ones, it forces a high white-on-black contrast) or click on the Stylish icon on a particular website and follow a link Find more styles to this site that will direct you to the Userstyles repository. It's a bit rough around the edges and can get annoying, but it transforms websites that look like shit into something you can actually read. If you would happen to need some help, feel free to ask!