This is an entirely functional in-game UI that has been made for the Skyrim Together mod, it shows various informations about members of your group, allows you to invite your friends and chat with them in the server, connect to a server via IP and a public server list, and also read detailed informations about the mod's network activity.
The main goal, art-wise, was to respect the game's original UI, and to keep it as vanilla as possible, while adding new Interface features that had never been implemented in Skyrim in the first place.
Since we couldn't just add to the original Skyrim UI, we had to inject a CEF (Chrome Embedded Framework) browser into the DirectX rendering system of Skyrim, adding another layer on top of the game, that works like a partially-transparent webpage. This led to a couple challenges regarding responsiveness, since people play with all sorts of resolutions and aspect ratios.