Overriding Fonts
If you have a specific font that helps you, on Firefox, you can overwrite my choices by changing your browser’s default serif, sans-serif, and monospace fonts. You can also change the default font size. The website shouldn’t break, either (though do let me know if it does). Instructions here.
If you prefer to only use a sans-serif font, you can set your default serif font to whatever your sans-serif font choice is.
For Chrome, you need an extension; its default font choices do not overwrite my choices. I can’t give a recommendation, as I use that browser as little as possible. I have no idea about any other browser; most of them are Chrome cousins, anyway, so you might need to get an extension as well. Try searching for some font customization settings, likely under appearance or accessibility settings.