Search plugin malfunctioning due to theme

I’m having a problem with the Ivory Search plugin, and the plugin authors say this problem is a theme problem. My website is http://www.katiesonger.com, and what’s happening is described in this thread on the plugin’s forum: on mobile devices, when the user tries to access the search box, the keyboard pops up and obscures what the user is typing. Can you tell me how to fix this issue?