40g aquarium not sitting flush on stand?

[Kammetal]

So this project has been a job in itself. I finally got the stand finished. I get my 40g breeder on after paying to have it drilled and I find that one of the corners is not sitting flush on the stand‍. So I took my level to see if it maybe was the stand and I’m seeing no gaps. I can slide a peice of paper under it. Now I’m left wondering if it is the tank? What can I do I have read about styrofoam ( even though it is frowned upon) or rubber mats I’m trying to save it please help

 

[ndrwater]

Hard to tell from the pic how big the gap is.
I would consider a yoga mat or something similar throat has some (can't think of a better term at the moment) "heft" to it.
Is the tank square? If the stand is level, the tank should sit flat.
Rimmed tanks need to be supported along the rim. They can crack from not being supported.
Worst case, shim any gaps where necessary

 

[Quietman]

Tanks with a rim only need support at each end technically. Can't see ever doing that myself. No need to put foam under rimmed either. You should be fine and dandy from how the pic looks.

 

[Backreefing]

You could slip wood shims under it in key places knife the excess off done