Refresh userstyles.css / userchrome.css without relaunch

I posted this in the Plugin development section many months ago. It didn't get any replies but did get a few Likes. It might be because this isn't feasible as a plugin and I perhaps should've requested this as a feature instead.

To reiterate, I'd like to see a feature that can reapply userstyles.css to the markdown rendering. Perhaps the user could choose between using a hotkey or auto-detecting whenever the file has been modified.

And yes, I know about pressing F5 in the development tools, but that reloads everything. It's only barely less clunky and time-consuming than just restarting the app.

And, if feasible, I'd like the same for userchrome.css as well, but I don't know if that's as feasible since it affects the entire UI. If it is, then perhaps they could each have their own hotkey and their own auto-detect options, as well as a hotkey for refreshing both at once.