First of all, I'm making gigantic heart eyes at this whole preview, you better tag me when this is done because I gotta SEE.

You've got a theme of slants going so far with the banner - incorporating them into the categories would be the first thing I can think of. Something right-aligned, like what Shiva said, would help with the balance of the forum, since everything so far is rather left-heavy. This can either be with an accent color, like the red, something just a shade or two darker, or even an image, like a cropped version of the banner... although, if you're going the pre-made route, that might be a little trickier. |D

One design I like a lot is having faint, larger text in the background, with the smaller (and more legible) text displayed in the foreground. Either the category name again in bigger text, or the name of the sight really faint in the background taking up just the same amount of space, but filling that space a little more with minimum effort.

As for general feedback, there isn't really much I can think to say, since it's looking really beautiful so far! Some nit-picky things, which definitely can be ignored since they're... small would be these: a) With the navigation tree, you have the background as the dark purple on the left, but on the right, it's got the same background as the rest of the forum. Especially when on, say, the home page, this is going to leave you with a lot of dead space on the right. Adding a background color alone can help fill that area - making it white, or a lighter shade of tan, for example - or including something that floats to the right, like a quick link toggle or... something???? I dunno, sdkljfhdskjfhds, could help with that balancing; b) and this is SUPER nit picky, hardly even an issue, sdkjlfhdksjfhsd the background image is darker on the left and lighter on the right, which makes the forum feel even more left-heavy, just since that's where all the darker accents are. Reflecting it might help again with forum-wide balance, or rotating it so the dark to light gradient is top-down or bottom-top may help. That's probably a lot of work for little payoff for something that hardly even needs fixed, though. >u>'

Shiva the Frostbearer Yeah totally! I put in a gigantic block there as a placeholder bc I was hating past iterations of it. Right-align sounds like a nice idea! ヽ(*・ω・)ﾉ

pharaoh leap I was afraid I was going too slant heavy and thought of something more square to ground the main forum, but if you put it that way I think I should stick with my guns and play with that theme throughout! (It'll probably anchor the overall look and feel too)

For the nav tree, I've been designing this between different computers and it always amazes me how different the colors feel on different screens (laptop, to computer monitor, geez) but I think you're totally right; the navigation links are also the same color as the forum bg and it doesn't feel important enough so I think I'll fiddle more with the styles (￣▽￣)b

TYTY for the suggestions!!

the hecking heck proboards hates tagging you for some reason leap

Quick update: I changed away from the candy pink to a more holographic theme (pinks/blues/purples). Now heavily inspired by BTS's newest song. And the trend of holo themed EDM album covers! 

*YELLS* IT'S GORGEOUS. Also, I think you solved your category title problem, because that's hot. *eyeball emoji*