Here is what I used in my button.tpl to produce a mouse over effect and it seems to work well, just change the colours to whatever you need. I also changed
Code:
<td class="Button"onmouseover="this.style.backgroundColor='#487600';"
onmouseout="this.style.backgroundColor='#335300';">
<font class="Button">{$button_title}</font>
</td>
And this is what I have for the class TD.Button in skin1/skin1.css
Code:
TD.Button {
BACKGROUND-COLOR: #335300;
padding:4px;
COLOR: #FFF;
FONT-WEIGHT: bold;
FONT-SIZE: 11px;
TEXT-ALIGN: center;
}