Menu sub items not working on iPhones

My site is here. I’m being told the Events and Media menu options (the only two with sub items/drop downs) are not working on iPhones. The drop downs work fine on a desktop computer or an Android phone, but not an iPhone. I’m told nothing happens when you click the words “Events” or “Media”.

I’m using a Twenty Eleven child theme. Does anyone know how to fix this? I found some threads for various other themes with snippets of custom CSS, but I’d love to hear from someone who has a solution for Twenty Eleven specifically. Thanks in advance!