Colapsed Menu

Hello,
Please, how can i adjust the area for small devices and tablets using Stacy Theme?
I think it is an issue of the menu. In the computer it works ok, but in small devices when the menu colapsed it looks like the menu it is hidden in a white area to the right that makes bigger the page even appears a bar on the bottom which move the page to the right showing a white area that makes the page weird and not responsive. How can i avoid the white area on the right side?

Thank you

The page I need help with: [log in to see the link]