CSS and a specific field in a custom template problem

Hey all

I have a little CSS question if anyone can help.

I have a custom form for submitting content with. The problem is all of the form input boxes are the same size, which is fine for all of them except one that I really need to be at least twice as wide.

Here is the code to call the relevant box

<?php print drupal_render($form['taxonomy']['tags'][2]); ?>

As you can see it prints a box for taxonomy 2, but its the same length as all the rest.

Heres the CSS code that defines how wide these boxes should be.

form input, form textarea {
  width:100px
  padding:3px;
  border:1px solid;
  font-family:Arial,Helvetica,sans-serif;
  font-size:0.9em;
}

So what Im basically asking is how would I over ride that CSS just for that one box? I believe if I name it in CSS then I can have separate rules for it, but I dont have a clue how to do that. Would anyone please be able to help?

Thanks