Help! Embedded app is messing up my search dropdowns for connected records

When I embed my app in a website, the dropdowns in my search menus are messed up, but only when trying to select connected records. When they are for multiple-choice options for the same record, everything looks fine. It looks like my website's theme (Avada) is messing with it. 

If nothing else, what I really want is for the background of the dropdown to be solid instead of transparent. Unfortunately, I'm not a CSS expert.

What can I do here? Please help! Here's a picture of what's going on: