responsive drop down navigation – drops down over images below

Hi,

Here is a link to the site i am working on: http://hotmomseries.com/

I’m having a problem on my mobile devices. The navigation turns responsive and becomes a drop down menu but when you click on the menu, the page titles / nav items are lost because they appear hidden behind the images that are posted in the page below. How can this be more effective? Is there a way I can add a background colour to the drop down nav? I tried and so far have been unsuccessful.

Please advise how this can be fixed to be more legible and clear.

Thank you!