Both Chrome and Firefox have removed Stylish from their extensions due to browser history tracking and privacy breaches. These CSS sets will remain, but Stylish will not. Source: https://www.bleepingcomputer.com/news/software/chrome-and-firefox-pull-stylish-add-on-after-report-it-logged-browser-history/
As an alternative, you may use the fork of Stylish called Stylus: https://chrome.google.com/webstore/detail/stylus/clngdbkpkpeebahjckkjfobafhncgmne
This repo provides a set of user styles (note: only supported use with Stylus add-on) for multiple sites that OSU IT services use, as well as a few user scripts (note: only supported use with Tampermonkey add-on). Basically, our in-house written "themes" for the tools we use at the OSU Service Desk under Information Services.
The original design for most of these sites is very white and required a decent amount of scrolling in some cases. These styles and scripts, developed by OSU IT employees, provide a better looking and more functional environment to the sites.
If you're looking for a specific developer or moderator, our contact list is here