decrease overall layout width of pinboard

Is there a way to reduce the overall width of my webpage without losing the sidebar? Before using Pinboard, I was using Evolve theme and you were able to choose the overall width of your site.

I switched to Pinboard when I was having some issues with Evolve and someone at WP made me a child theme. It works great and overall I am happy, but sometimes I feel like the layout is so much wider that my website looks weird.

I have tried applying some of the suggestions about changing layouts to my custom css, but nothing has worked.

My site is freshkitchenandbathdesign.com

Thanks!