Aptana gives me a warning saying "<html>
has XML attribute xml:lang"
Here is the line. What's wrong here?
<html xmlns="http://www.w3.org/1999/xhtml" lang="en" xml:lang="en">
your code is fine, it's the bug of the built-in HTMLTidy validator
I've found the answer here: https://aptanastudio.tenderapp.com/discussions/problems/3034-templates