Underline Submit Buttons with CSS in Mozilla

I'm trying to use CSS to make Submit buttons that look like text links (so they match other text links on the page). Background color is the same as the page, no borders, etc. It works great in IE, and everything works in Mozilla except for underlining. Am I doing something wrong, or does Mozilla not support underlining for form buttons? I've searched the Web and haven't found any info on this.

CSS definition:
input.add {
font-size: 9pt;
text-decoration: underline;
color: #000000;
background-color: #FFFFFF;
border-width: 0px;
border-style: none;
cursor: pointer;
}

HTML:
<input class="add" type=submit value="Submit">

I really appreciate any suggestions or insights on this!

You could just use an ordinary blank link, and use javascript to submit the form:

ie:
<a href="#" onclick="document.getElemntById('form').submit();">submit</a>

Any use?

you could set a color to border-bottom instead,

input.add {
font-size: 9pt;
color: #000000;
background-color: #FFFFFF;
border-width: 0px;
border-style: none;
border-bottom:1px solid #15f;
cursor: pointer;
}

Thank you for both tips. I tried the JavaScript idea, but I can't assume that the people who use the site with have JavaScript enabled. I ended up with setting the border-bottom, and that looked good in Mozilla, but not quite right in IE. So I had to use some CSS hacks to get the right stuff to each browser. Thank you!