Now, word of warning, I'm an accessibility and efficiency consultant. I specialize in websites and how things like legal woes over WCAG (web content accessibility guideline) violations can in fact create problems under the US ADA, UK EQA, etc, etc. As such my comments may get a bit technical.
From that standpoint, THIS SITE HAS PROBLEMS. Nothing insurmountable, but there are big issues with the style of it.
The biggest of which being the white text on green and vice-versa that fails colour contrast minimums. This isn't rocket science to check, there are nice handy tools to help with this! You've got #80B600 (a green) and #FFFFFF, if we plug those into webaim's excellent tool:
webaim.org
We find that it fails EVERY level. Given how the WCAG was created pre font-smoothing I would consider "Normal AAA" as the bare minimum, and that color is light-years away. For the buttons it could probably be retained if sufficient text-shadow were added, but for all the stuff that's green text on white it's utter garbage typical of choices made by an artists under the DELUSION they know what design is.
Which is why I use a user stylesheet override to force this site to be usable.
Another big issue is the use of absurdly undersized "fixed metric" (aka pixel) declaration fonts, leaving users on non-standard metric machines (like every one of mine) diving for the zoom. It's called EM and REM, use 'EM. 99% of the time you see anything declared in PX on a website's design, you're looking at the pesky 3i of web development: ignorance, incompetence, and ineptitude. That's not really on you guys, as it is on the creators of whatever forum software this is.
I don't dare pop the bonnet to give the code an evaluation. Forum software can often be some of the ugliest garbage in that regard. Only way they can be worse in that regard is if they get garbage "frameworks" like Bootcrap or Failwind involved.