The problem I think is a lack of knowing what CCS can do:
Currently your button.tpl tests for Microsoft and if IE uses a mind dead button. They embedded the image names and size and the size is not valid (no type like px or pt). They also use an image fill in the <font> tag and a tag that only IE knows <nobr> .....
X-Cart button.tpl: (what this does is embed Javascript in your page, if the customers have Javascript turned off this fails)
{* MAKE SURE YOU HAVE NO REDUNDANT CARRIAGE RETURNS IN THIS FILE ! *}{if $type eq "input"}{assign var="img_type" value="INPUT type=image"}{else}{assign var="img_type" value="img"}{/if}{capture name=goimage}{include file="buttons/go_image.tpl"}{/capture}{if $style eq "button" and $webmaster_mode ne "editor"}<SCRIPT>
if (navigator.appName.indexOf('Microsoft')>=0)
document.write('<nobr><{$img_type} src="{$ImagesDir}/but1.gif" width="7" height="14" border="0" align="absmiddle"><FONT class="Button">{$button_title}</FONT>[img]{$ImagesDir}/but2.gif[/img]</nobr>');
else
document.write('<font class="FormButton">{$button_title} <{$img_type} {$smarty.capture.goimage|replace:"\r":""|replace:" \n":""}></font>' );
</SCRIPT>{else}<font class="FormButton">{$button_title} <{$img_type} {include file="buttons/go_image.tpl"}></font>{/if}
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I had to modify my button.tpl:
[img]{$ImagesDir}/lefts.gif[/img]
<span class="ButtonBack">{$button_title}</span>
[img]{$ImagesDir}/rights.gif[/img]
and add class="Button" to the <a > tags that call button.tpl
Then modify skin1.css:
a.Button {text-decoration: none; FONT-FAMILY: Arial;font-weight: bold; font-size: 11px; font-style: normal; font-variant: normal;}
a.Button:link,A.Button:visited {COLOR: #97C0C1; font-style: normal;}
a.Button:hover,A.Button:active{ COLOR: #FFFFFF;font-style: normal; font-size: 11px;}
.ButtonBack {BACKGROUND-COLOR: #a54579; vertical-align: middle;}
.ButtonLeft{margin-left: 0px; margin-right: -3px;line-height: 9px; padding: 0px; vertical-align: middle;}
.ButtonRight{ margin-left: -3px; margin-right: -0px;line-height: 9px; padding: 0px; vertical-align: middle;}
The net effect is text that changes color on mouse over and a button that works on IE/Mozilla/Firebird
X-cart really needs to have every tag "classed" from the database.
I had to edit cart.tpl/gifcert.tpl/add_coupon.tpl/checkout.tpl/buynow.tpl to add the <a > class
Of course if you do this you can not use the patch system to upgrade.