I'm trying to get a layout together, but two things are giving me a hard time:

Is it possible to hide the achievements and shows bars completely? I managed to poof the events one, but if I try the same with the other two it also hides other stuff, like the description box.
And would anyone be able to share the secret on taming the menu? Even with all the amazing layouts I come across, menus that are centered main and sub alike seem few and far between. I may very well be missing something obvious here, but it's got me stumped all the same.

Any pointers or advice would be much appreciated!

cant help with coding but I can give you a bump :)

Actually

 ul#nav .selected a, ul#nav li.selected > a  {
        background:transparent!important;
  }

^^ That should make the background of the nav bar tranparent when you click it and it drops down I may be wrong. I am just grasping coding and CSS again. As for centering it - despite having my stuff set up to be centered - I haven't managed to get it just yet.

I have to rediscover how to center the nav menu every single time I try to do it lol; I'm afraid I won't be much help there. Something about removing the floats on both the main and sub menus, I think?

As for the Achievements and Shows sections, I believe those are impossible to remove completely. You can always make it so that their content doesn't display, but the table headers will still be there. I just experimented up, down, and sideways (as much as I'm able to on mobile :P), but there's no way that I know of to remove those links. You might also want to keep in mind that HP's rules may require those sections to remain visible on the page, like all links and player info (probably need to check with an admin on that).

Yeah, the shows-achievements-events part, that might be a total no-go. I discovered that when I managed to hide the events bar, one of my horses randomly went into hiding too. Was a good laugh, but however those things work, they're not meant to be manipulated individually it seems.

Floats, floats, I'll have to see about poking around in that direction, thanks!

(On a side-note, as someone only recently discovering Mass Effect and playing through it all, I greatly approve of your signature!)