Made this in an afternoon because I thought it’d be a fun CSS challenge. Ended up having to program my own inventory bar, spawnlist, and other UI menus due to the additional functionality I added.
The addon spawns an entity that you can interact with to enable/disable the UI reskin at will (yes, you can return back to the original Sandbox UI whenever you want)
Some things are purely visual and do not function, such as the search bar above the tools and the search bar in the Local Models tab. However, it’s pretty faithful to gmod looks and retains basically the same functionality as the base Sandbox gamemode.