Wide Images / Galleries within a post

Hi!

I’m trying to come up with a way to make certain images or even a gallery within my post (other than the featured media above the title) appear just as wide as .featured-media => the full width of the wrapper rather than just 700px.

I tried to implement a new .wide-content class by reducing the margin-left and -right, but it only worked on the big screen and was not responsive.

Maybe you have a hint for me? That would be great!