Full width Color behind Media Elements in Posts/Blog

I am trying to figure out if there is a way to create a color section in a post or blog. The client is required that there be a solid full width color behind two media elements (video and image). I have created the video and image in the 1/2+1/2 layout but I need that to be wrapped within a full width dark gray color bar. I tried using <div style=”background-color:#333;”>CONTENT HERE</div> but it didn’t work. It works in the wordpress admin area but not the actual page.

I also want to have the post use the alternative white background instead of the light gray and I tried using the div tag again to make that happen but it will not go full width. There is a border around the post that is preventing it. I am sure this is a css style I can change just for blog posts. Any suggestions?

Thanks,
Connie