Problems changing the date in the calendar control on the booking form.

I've been working on getting OSServiceBooking working on our site and I'm having a problem with changing the date on the calendar. At first, nothing worked on the data control block above the calendar. Then I found a forum post with a similar problem and added the fix recommended in that post:

#calendardetails .btn::after {content: none !important;}

Now the [Go] button fires but still nothing else works. Neither the month nor the year drop downs open or react and the next month [>] button doesn't do anything. When I click on any of these or anywhere else in the block other than the [Go] button, the block just flashes to briefly to a lighter color and then nothing happens.

I've tried different browsers and all sorts of different settings but nothing has helped.

Thank you.