firefox-css VS Firefox-Mod-Blur

Agreed. Sidebery is fantastic, especially with some userChrome.css tweaks like https://github.com/dexeonify/firefox-css

I use Sidebery along with this custom CSS someone wrote for it

This is my first time doing something like this. I though I just need to add files to the chrome folder, but that doesn't work(at least for some files). 2 files that should hide my extensions and hide my bookmarks doesn't work. Can anyone help me? I've followed instructions from here.

Here

Yep! Use the privacy mod here and place it in your userChrome. You have the option of having blurred out email in the main menu, sync menu, or change the email in the main menu to any other text you want

You can find more information on extra features and code here https://github.com/datguypiko/Firefox-Mod-Blur

I've been struggling hard with trying to make my address bar suggestions box transparent. I got inspired by [datguypiko's Firefox Mod Blur], and wanted to implement some of the transparency stuff into my userChrome.

try that code but first download this image

I use the theme from here without any changes.

Not true, here is an example using it for the search bar. I use this with sway wm which does not support blur.