> A late response, but watch that if you're using other people's HTML,
> class values are ascii-case-insensitive.
>
> XPath 3.1 and XSLT 3 have fn:contains-token(@class, "foo") to meet this
> use case more precisely.
>
>
https://www.w3.org/TR/2017/PR-xpath-functions-31-20170117/#func-contains-toke
n
>

To match the HTML5 semantics precisely, you also need to use the right
collation, which has been standardised for the purpose:

contains-token(@class, 'foo',
'http://www.w3.org/2005/xpath-functions/collation/html-ascii-case-insensitive
')

Michael Kay
Saxonica