For FO customization:
<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
xmlns:fo="http://www.w3.org/1999/XSL/Format"
version="1.0">
<!-- Make <guibutton> looks like a button. -->
<xsl:template match="guibutton">
<fo:inline border="1px outset #dddddd"
background-color="#dddddd">
<xsl:call-template name="inline.charseq"/>
</fo:inline>
</xsl:template>
</xsl:stylesheet>
For HTML customization, include the following in the Cascading Style Sheets(CSS)
.guilabel
{
font-weight: bold;
}
.guibutton
{
border: 2px outset #dddddd;
background-color: #dddddd;
}