A talk I gave at the European Plone Symposium 2009 in Sorrento So you have a big legacy portal application which you want to change the look of, but are contractually not allowed to touch? Here is a case study on how we used the power and flexibility of python and wsgi and the wonder of lxml to dynamically re-skin a proprietary .NET portal without even touching it. We take a giant lump of messy invalid HTML markup and dynamically strip it back, add semantic markup and CSS and present the user with a nice svelte valid site.