Just going to start with my critiques are out of order, I apologize lmao.
I'll see what I can do constructive criticism wise, it's hard to picture how this would actually look and act in action, but lets see.. For the portal, I'm a tad confused on what the colors of the balls indicate if anything, I would either streamline it or not have them there kind of confusing. The reason why I say it's confusing is because I was trying to see if a color would line up with some sort of function, such as Photo sharing, awards and achievements, would be two plug-in features, but doesn't seem like it. Speaking of that I would like to see a bit more organization on the portal there perhaps grouping actual features of the forum together, such as what I referenced a second ago. But don't get me wrong it is clean.
For the Toplist deal, I would say, the gradient from deep blue to that gray, is kinda odd, hard to imagine multiple up there, could look a bit wonky, maybe try a solid color? Also at the top right not sure how you would mark it as read there, is this going to pop notifications to people on the forums? Not sure how that would work out there. But again clean nonetheless, I like the color scheme.
For the actual avatar I would just put rune/code no need to put no avatar, as you're making that their avatar.
Logo, not knocking it but I feel like I've seen it a million times, just because any avatar with code in it looks about like that, also the C is a bit off there,
https://i.imgur.com/cCnx8gO.png. Now just because I've seen similar things to it, doesn't mean I hate it, obviously people do stuff like that, because it looks great.
Now with the Premium I feel like that whole box can be reduced in width, would look a lot more clean. I'm actually liking the gradient of the sections there though. Also the banner at the top could perhaps look a bit better if you reduce the height of it? Has a lot of blank space on it t'word the bottom. Again looks clean, and goes with your theme well.
Overall I like it, but I would really have to see it in action to provide solid feedback, on how things look there.