Hello, I'd like to make an addition, via function.php, to make a plugin behave properly. I've fumbled around with a bit and only managed to get more errors than what I've started out with.
This is what I have to change/add - somehow
Valid XHTML If you're using XHTML, the custom attributes will not pass validation. To make your XHTML technically valid, you'll need to add a custom namspace declaration to your opening <html> tag. (Note that the W3C validator does not take custom namespaces into account.) Change <html xmlns="http://www.w3.org/1999/xhtml"> to <html xmlns="http://www.w3.org/1999/xhtml" xmlns:addthis="http://www.addthis.com/help/api-spec">