I added the WooThemes plugin for Product Add Ons located here:
http://www.woothemes.com/products/product-add-ons/
Everything works perfect, with other themes. However with yours there seems to be a display issue on single products. This also happens on mobile too.
When you select the add-on option, a drop down showing your new totals happen right above the “ADD TO CART” button. However with your wonderful theme, it’s just black.
I have an example in the private area for you to see.
Any help?