vertical positioning of inline li text relative to background image

I'm using an ul as an in开发者_Python百科line menu, with a background image for each li. The ul is absolutely positioned. No matter what I do I don't seem to be able to move the text of each item vertically with respect to the background. Horizontal is fine with text-align: center. The background for each 'button' is of critical height as I am integrating two third-party sets of software (classifieds and bulletin-board) into the site as a whole and tailoring the biulletin-board to have the same look and feel as the classifieds, so I can't change the height of the background. (The classifieds system using some very complex java to produce backgrounds with curved corners that are made up in three parts!)

How do I go about setting the text position vertically in relation to the position of the background image.

Tried using the line-height:

ul#id-ul li  {
  line-height:20px;
}