Weird border on mainbody position

Hello all,

Setting up the template just now, I installed the full demo package and started to strip out modules that I didn't need. I want to display something simple on the mainbody position, whether I do it with a Custom HTML type or ArticleAsModule type module on the mainbody position, I get these weird borders on the right and bottom of the module itself. Does anyone know how to remove them? Any help would be appreciated.

doublepost.. .see the other answer