Header image problem when using site from a small screen


We’ve been struggling with our site for a while since it breaks up in smaller screens. The biggest problem is the header image: it won’t fit right to the site when screen is small enough. How to make it move with the site right? We have a child theme of the travelify theme and we have made all the changes and the site is here http://users.metropolia.fi/~marilei/wordpress-3.6.1/wordpress/

Many thanks in advance!