Add classname to menu <ul>

It would be nice if there was a possibility to add a classname to the specific menu < ul>. Because if you use

ul.menu li a {
  display: block;
  width: 100px;
  height: 20px;
  text-indent: -9999px;
  overflow: hidden;
}

...this will apply to all the menu's.

I solved this by using the block-id, which is longer and is 3 div's down the menu < ul >. It's just an idea.