The following instructions were written for the Resource perspective, but they will also work in many other perspectives.
Follow these steps to add an HTML template to your XSL file:
The following text will appear in the XSL file:
<xsl:output method="html" encoding="UTF-8"/>
<xsl:template match="/">
<html>
<head>
<title>Untitled</title>
</head>
<body>
<xsl:apply-templates/>
</body>
</html>
</xsl:template>
The <xsl:apply-templates/> element will recursively process all the children of the XML document you apply your XSL file to.