Trouble setting my site to full bleed all borders.

Site URL: https://www.strategicartsgroup.com/

Hello friends! I'm new to this, and managed to imbed my Slides images into my URL in a string, but don't know how to make the frames of the blocks go to full bleed. I'm getting a browser's border rather than the blocks going to the edges and expanding/contracting with the browser. I tried some CSS code but it made no difference. Any help would be really appreciated! 

You simply need to extend the blocks into the gutter, drag the handle on each block left and right to extend to the edge of the screen.