Drop down top menus

I would like some help with the catch kathmandu pro theme. I have a large top menu with my pages, the pages need several drop down sections. this works well on the web page but on the small screen ie iphone the drop down menu comes out as one long menu when clicked. is it possible to change the css here to make the menu so that each category must be pressed before the menu items under it come out on the smaller screens? how can this be done? thanks for your help. please check hokkaidoguide.com thanks gareth