ShopIsle: Problems with mobile responsiveness

Hello. I am using the Shopisle for my WordPress site and I have a problem with its mobile responsiveness.
My images look great on desktop, but way too large in mobile version. This problem is foremost visible on the frontpage slide. I also have this problem with my text headers. It’s like the theme isn’t adapting them for mobile, because they seem too large compared. Someone know how to solve this problem?

Thanks in advance

The page I need help with: [log in to see the link]