Responsive Website and Jumping Divs

My website is fully responsive, and I think that’s part of the reason #side_post" jumps here . can anyone suggest a way to stop the jumping without giving #side_post a width?

#side_post does have a width at the moment. But there are a few problems with it, such as the top being hidden by the fixed nav above it. Even with a “responsive” design, it’s better to give each element a clearer idea of where it is meant to go, as things seem to float around the page a bit here. Anyhow, how do you want that #side_post to appear/behave?

Ok, I seem to have fixed the jumping on desktop view, but it’s still jumping on mobile. Any ideas?