Here's a screenshot, in case there's any other issues I'm not aware of between browsers or something, since that tends to happen with my code. Heh. (Im using Chrome on a Macbook.)

See that square in the bottom left-hand corner that isnt the same color as my main profile section? What's up with that??? Here's my background code, as well as the bit above it, because I'm not sure, but I don't think that other part should affect the body background image?
,.comment_table,.header,.block,.info_block {background-image: none; border:0px;}
body,html { background-repeat: repeat-y; height: 100%; width: 100%; background-image: url(http://i.imgur.com/sir0SWb.png);}
Heads up in advance that I might have to edit this post, it's not letting me preview it for some reason so idk if my formatting is working P:
Im sorry i just. get SO Frustrated with the way this profile system works. I feel like I have to re-learn how to make profiles EVERY time I make a new one because it's not as simple as just putting my code in, I have to remember which columns go where and what's in each column and oh my god it's just too much for me to keep track of, I have extremely short-term memory 3: I even took notes in the code of this profile and it's not jogging my memory at all, lol. Whoops.
So is this like, an issue with one of my sections, or?

Edit: And before I forget, I think I remember reading somewhere that you actually can't change this, but I want to be sure; when you click into the comment box and the whole thing has a grey selector glow around it - that's something to do with my OS and not my code, right? Or can I remove that so there's no glowing border? It's just a pet peeve of mine idk
Since your background is this and you have it set to repeat on the y-axis, it will repeat going down rather than continuing from the bottom color. Or the dark green color to the right. If you're looking to replace it with the dark green color on your profile, use this code.
,.comment_table,.header,.block,.info_block {background-image: none; border:0px;}
body,html { background-repeat: repeat-none background-image: url(http://i.imgur.com/sir0SWb.png);}
EDIT: Unsure if that code will cover the green area as well since I removed the height/width-100%.

Hmm, thank you! I think maybe it was just the background I was using?? Cause I tried replacing it with different backgrounds/different sizes and plugging it into your fix there and its working now. :I So that might have been a lapse of judgement on my background choice I guess
Im really not sure how I made it repeat everywhere except for that one little corner, but as long as it's covered I guess I don't really care //shrugs