Flyout submenu disapears behind right edge of window.

Im trying to start up a new site, craftersu.com, which will contain a hole heap of different categories and subcategories several levels deep. Therefore it is crucial that the menu works perfectly, which it doesn’t at the moment. The problem is especially clear when viewing the site from a mobile phone, but occurs for desktop viewers too. The sub menu fly outs only seem to fly out to the right, which leads to the menu choices on the right getting their sub menus hidden beyond the right edge of the web browser window/mobile screen. is there any theme, plugin or hack that can make the sub menu fly out to the left if theres no room left on the right?

I’m using Twenty eleven, but this problem has existed in every theme Ive tried, including all of the featured ones…