(currently not in working order in current build of Payday 2) :(
However theres some cool BLT mod out there that allows it to work with the current build (or any other skill tree menu background mod for that matter)

Suggested/requested by Tman2bard.

Replaces skill tree backgrounds with "radical" pictures of the crew from Cowboy Bebop.

Currently only works with non-beta game since with skill beta game, the skill tree backgrounds are no more...at least for now.

Want a Cowboy Bebop main menu/loading screen background?  Here you go.
https://modworkshop.net/mydownloads.php?action=view_down&did=16258

If our Overkill overlords decide to introduce the backgrounds back to the skill tree beta, I will update.

Oh and this is mod override format.