Make Site Full Width – remove left margin

Hi, I'm currently working with the Simple-Catch theme and would like to make my site a full-width design (as in Catch Theme's Full-Frame theme). Whenever I expand the width of the header or the image or the content area however everything expands right leaving a very noticeable left margin. I cannot for the life of me figure out where this left margin is coming from. Is there any way to remove it? http://www.bbigwords.com/ Thanks!