Full Frame: Featured Content Background Image on Mobiles

Hello, Hope someone can help me. I use Full Frame theme on my website. Everything is great, BUT I have an issue with the background image of the featured content The image appears great on the laptop and on the previews for tablet and mobile, but when I actually view my website on my iphone or ipad the image doesn't look good at all, just looks like a blurry zoomed in part of my image, not good. Please help :)