To support students with dyslexia / other needs, you can also add an Accessibility toolbar to your pages. This way students can choose for themselves which colours work best for them as it does vary a lot per person.
See the "Accessibility toolbar" link in the footer of our testsite: https://moodle.capel.ac.uk/testmoodle/
When you click on the link, you'll get a toolbar at the top of the page. With this toolbar, you can have text-to-speech, changing text font/colour and text overlays. It's open source, developed by the University of Southampton: https://www.atbar.org/
I have added it to our footer, so it's there throughout the site, but you can add it anywhere you can add a link with Atto / TinyMCE. Just "right-click > Copy link location" on the Accessibility toolbar link on our test site, then add it to your Moodle if you want to.
(I have yet to figure out how to make the settings stick on every page, like the no longer maintained Accessibility block could do)