Well, the addition of the default.css from NoNumber! default menu did the trick. I modified it to fit my height/width and did some tweaking to the padding.
I think the trick was the display: inline-block on the a, hover and second span.
I took care of the padding on the individual normal, hover and active spans due to each button being a different size and with Hide Text set to "yes" on the module, the size of the <a href> element was left to a single space (about 3 pixels wide).
Here's what the final CSS looks like:
/* ---------- CUSTOMENU STYLING ---------- */
div.customenu_topmenu {
}
div.customenu_topmenu,
div.customenu_topmenu a,
div.customenu_topmenu span {
margin: 0px;
padding: 0px;
}
div.customenu_topmenu a span span {
float: left;
height: 35px;
padding: 0px;
text-align: center;
cursor: pointer;
}
div.customenu_topmenu a,
div.customenu_topmenu a:hover,
div.customenu_topmenu a span span{
font-size: 12px;
font-weight: normal;
text-decoration: none;
color: #000000;
display: inline-block; /* NEEDED FOR IE ON MAC */
}
/* ---------- BACKGROUND IMAGE STYLING ---------- */
/* HOME */
.customenu_topmenu a span.span_link_1 span.span_normal
{
background-image: url('/'../../../images/stories/top_menu/top_menu_off_01.png'');
background-repeat: no-repeat;
padding-right: 50px;
}
Thanks for all your help! This was definitely tricky but well worth it. I'll make sure to leave a great comment on the joomla extensions page!