Vertical bar the height of a div

Hello,

I am trying to create a vertical bar that acts as a giant next button that runs from the top of a div to the bottom without using fixed values.

Currently, this code does not seem to inherit the height of the div and instead takes on the height of the graphic stored inside the bar instead, which is only about 30px high. Any suggestions are appreciated.

CSS:

[code]
#mainText{
float:right;
width:750px;
background-color:#fff;
margin-top: 25px;

}

.navButtonLeft {
float: left;
width: 32px;
height: auto;
padding: 15px 0;
margin: 0 15px 0 15px;
background: #7799bb;
}

[/code]

HTML:

[code]
<div id=”mainText”>
<a class=”navButtonLeft” href=”Link to next page”&nbsp;<img src=”/arrow.gif” alt=”next button”/></a>
<p>Lorem ipsum dolor…</p>

</div>
[/code]

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