Header not resizing properly from desktop to mobile (Genesis News-pro)

In relation to the following site:
https://www.englishenglish.biz

– When I resize my site from desktop to tablet, the header doesn’t resize and instead crops the left and the right sides.
– Also the Genesis responsive slider doesn’t resize smoothly.

– When it gets a little smaller than tablet size, the header clicks back in to correct width, and begins to scale down correctly – however there is a large white space under the header.
– At this size the Genesis responsive slider now starts to resize as it should.

I’m really puzzled as to what is causing the bugs with the scaling down.

Any pointers would be greatly appreciated.