Page Size issue after using WP Cache

Hello all,
I recently activated WP Cache to get better pagespeed results (they were showing as low as 2 out of 100) however I believe this made the theme not display properly. It looks fine on desktop, and when viewing with chrome on mobile the index page appears normally – however when you click the sidebar its too wide, thus making you scroll sideways.. It didn’t do this before and even after I’ve deleted the plugin and reinstalled the theme the issue still appears. The site is thesquareface.com if you need to take a look.
Thanks for taking the time to read this, and also for any help you can give.
Kind regards,
Alan