It works

Is it possible, by any chance, at some point, to get something like uBlock's procedural cosmetic filters for our UserCSS scripts? CSS is great, but it's a bit lacking in functionality, especially in regex support.
I'm only starting to learn JS, and I imagine it's gonna take a while before I'll be able to write the scripts I need.
Thanks for all your hard work!

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The UI is much better and more intuitive than that of TemperMonkey.

I really like the distinction between CSS and JS modifications and that I don’t need to use “proprietary” GreaseMonkey functions like GM_addStyle (` /* the CSS goes here */ `).

FireMonkey also doesn’t exhibit the bug that TemperMonkey does — when I navigated the same portal over many pages, it seemed TM kept adding the same CSS script over and over, which, over time, slowed Firefox noticeably (after a while TM reported aplying about 70 scripts instead of 2!).

Perfect better than the alternatives.

It is indeed super lightweight. A nice advantage to being on Firefox, as it's not available elsewhere.