YouTube ReturnBoxes wót JX_Snack

This is the FireFox version of the "ReturnBoxes" extension.
Features:
- Better thumbnails
- Better description
- Red subscribe button (that also makes almost every other important button red, not the normal ones.)
- Better subscribe popup
- Better searchbox
- Title has normal font again
- Background of normal buttons transparent (like in the old layout)
- Dark mode compatibility
- and lots more...

Extension Support:
- YTDL Crop (YouTube Downloader by Addoncrop)
- Fixed download button
- Made download button fit into the theme