If someone would like to try this in Firefox (or other browsers), one could simply install a userscript manager browser extension such as Greasemonkey and use the code from convert.js.

Here's an example of how I added the functions to all websites in Firefox/Violentmonkey: https://pastebin.com/ZE75x0Uw

Here's a screenshot of what it looks like: https://imgur.com/a/bP3bUFP