Horizontal-Stack width after upgrade

I just upgraded from 0.114.4 to 2020.12.

This broke my horizontal-stack because of an incorrect formatting issue that was ignored before, but not now.
https://www.reddit.com/r/homeassistant/comments/jmpgy4/after_updating_lovelace_cant_find/

Now that I fixed that, my Horizontal stack is only using about 25%-30% of the total browser window. Coming up empty on why. I have commented columns of the horizontal stack and the problem persists. With three columns, each takes about 10%. Two columns, each takes 15%. One column takes the full 30%. But nothing takes the whole window like it used to.

I tried setting panel:true. That makes it take the whole window, but it is the WHOLE window (no padding at all) and the badges disappear.

Any help would be appreciated. I posted the code here.

Thanks in advance!
~Jon

One thing I note is that you still use custom_header, which has been deprecated a few releases ago.

Yes, I am planning on switching that out. I did find a workaround but it will be worth switching back once I remove the custom_header. Thanks!