Dropdown menus dissappeared

Hi I just wondered if anyone could help?

I'm trying to get the dropdown menus working again for this site:

http://www.yorkmodelmaking.co.uk

The categories horizontally across the top used to have dropdown menus as they should in this theme used here:

http://tzelewski.co.uk/template/kinder15/

I've emailed the theme developer but it doesn't seem to be supported any longer...

Can anyone please help fix this and get the dropdown menus working as they should again?

Thanks for any help at all.

Add the following to your theme css

Thank you! Great fix - though I wonder why that was missing from the css... Very odd. Thanks again!