Images on post page are not responsive

Hello,
I can’t see the responsiveness working. When I resize my browser, the images stay the same size.
http://olympian-builders.com/otw-portfolio/brooklyn-coop-renovation/
I also tried adding “max-width: 100%;” to otw-portfolio-post as well as in some other places, but it hasn’t helped.
Any ideas how to make this responsive?
Thanks.

https://wordpress.org/plugins/otw-portfolio-light/