What do I have  to do to change

<pre class="codeblock"> 

in xhtml output to be:

<pre class="prettyprint">  ?

I want to do this in order to use the Javascript code prettifier to format code. I have args.hdf set to write the script call in, and the args.css set for the style sheet, but I am not sure which template I need to copy into my custom .xsl to change the actual tag in the xhtml.

Fast solutions appreciated. ;-)

Julia