[Theme Nouveau] Making Page Full Width

Hi!

I would like to make my blog posts full width to allow full width images that span from edge to edge of the screen as in “post example 3” in this website: https://justfreethemes.com/demo?theme=Abito
But at the same time, not ruining the layout of the text or other elements such as the header.

Being an amateur at coding, I tried to insert css into the custom css box of my theme but when the single post container width was set to 1960px, there will be a space on the left side of the image and the header and comments would expand along with the image which I do not want.

Here is the link to my site: https://gabrielleschadt.com/food-photography-clean-and-fresh-styled-shoot/

How can I do this? Is there custum css I could use to make a blog post full width?

Thank you so much in advance!