Styling widget outside container boundaries: sizing works, content cut off

I am attempting to style the Latest Posts widget to explode to 100% width (outside the container boundaries) by setting left and right margins to -3000 and padding to 3000. Although the widget does properly scale to page width, the visibility of the thumbnails remains within the container boundaries, creating a viewport effect. I'm looking at the html generated by the widget and it's a complex set of UL/LI combinations. Can you give me pointers as to how I could achieve the desired result?

(highlighted area shows page width for wpcufpn_container and content cutoff at site/main container boundaries)