fullwidth image on page with sidebar

I’d like to have images with zero border (flush left and top of surrounding content). I can’t use the fullwidth slider for a single image, nor can I use a color background since it is fullwidth for the entire page and not just the main content are on a page with a sidebar. I also tried editing styles for things like…

.page-id-43 div.template-page .content .av-content-small .units { margin:0px !important; padding:0px !important; width:100%; }

… but that (being one of a dozen or so similar attempts) didn’t work. Please let me know if this is possible!

Thanks