How do I get the T3 BS3 Blank template to span the entire screen and not have the large spaces on either side?

I have opened the unedited T3 BS3 blank template in three different browsers and each time there is a large empty space on both sides of the template the sidebars are both nearly 150 pixels from the edge of my screen. How do I get the template to span the entire screen without the large borders/spaces at the sides?