how do art work on steam like that

same here

I though the same :).

people are so original these days, they don't even work on the pieces themselves...

look how unique my profile is!

*checks 500k profiles, all the same*

*facepalm*

It's like learning tooth fairy is not real. :(

Before that website you had to download the background from Steam cache or third party site and use a photoshop template to cut the right pieces + alignment problems/adjustments after upload on Steam cloud. Now it's easy :p

As far personalisation goes, you can modify the central artwork piece and it even accepts animated .gif

I thought the same. I always give people too much credit, I should have known better.

I did make mine entirely by hand, I event added a subtle animation no one noticed yet.

Here's a reply for you! Even easier to search.
Steam Profile Background