Dropdown Menu Bug

Hello,

Great plugin, I am using the premium version. I noticed a bug with the dropdown menu to select number of spots.

What happens is that the numbers all appear hidden until you scroll over them. I was able to produce this error on Windows 7 latest version of Chrome and Windows 10 latest version of Edge.

http://imgur.com/a/W4oUg for screenshots of this bug.

Site is at http://www.vernoninternational.ca/summer-programs-booking-form/