esconder menu (dropdown) para moviles

[helenp]

The problem is in the css,
didnt thought about it,
I tried to add a display: none to a hover.....and some devices dont understand hover..

This editing the css in firefox and chrome for pc takes away the dropdown and that was what I was trying to do:
div#menu ul ul ul li:hover ul {display: block;}

Know I am putting display block on all kinds of ul's and li's and still the same.....
what can I do?