Vertically centering an anchor within spans and li with css

I'm using jQuery tabs, and I added some spans to the tab headers so I could use a background image. Here's the markup:

<ul>
    <li><span class='tab_outer'><span class='tab_inner'><span class='tab'><a href="#orderInfo开发者_运维问答">
        Order Info</a></span></span></span></li>
    <li><span class='tab_outer'><span class='tab_inner'><span class='tab'><a href="#notes">
        Notes</a></span></span></span></li>
    <li><span class='tab_outer'><span class='tab_inner'><span class='tab'><a href="#eventLog">
        Event Log</a></span></span></span></li>  
</ul>

The problem: the text inside the anchors is displaying on the very bottom of the anchor's block. If I could just move it up like, three pixels, it'd be perfect. Here's all the CSS that I think is relevant:

.tab_outer, .tab_inner, .tab
{
    display: inline-block;
    font-size: 11px;
    list-style: none;
}

.tab_outer
{
    margin-bottom: -3px;
    padding-right: 3px;
    margin-top: 4px;
}

.tab_inner
{
    margin-bottom: -1px;
    padding-left: 3px;
}

.tab
{
    margin-top: 0px;
    padding: 0px 4px 0px 4px;
    margin-bottom: -1px;
}

Try the line-height and vertical-align properties:

.tab_outer  {
  line-height: 32px; /* Put the corresponding size here */
  vertical-align: middle;
}

Alternatively you can adjust the padding:

.tab_outer {
  padding-bottom: 3px;
}

margin: 0px;
padding: 0px;
vertical-align: super;