What do you mean by loading two ways the css?
This is the first time the stylesheet is loaded. Done in a not really standard way.
<!-- I linked to the stylesheet using two methods, the @import method as well as the link rel method, to ensure maximum accessibility -->
<style type="text/css" media="all">
<!--
@import url(http://www.angiesbeautycare.nl/wb/templates/a_bit_modern/styles.css);
-->
</style>
This is the second time the same stylesheet is loaded. Done in the standard way.
<link rel="stylesheet" type="text/css" href="http://www.angiesbeautycare.nl/wb/templates/a_bit_modern/styles.css" media="all" />
For some reason FF (at least the firebug plugin) is really using both of them as separate stylesheets.
I would suggest to remove the first code part from your template/index.php.
If it doesn't solve it right away, at least it will be easier to debug.
Ruud