Xml file formatted by CSS prob - not showing formatting

OK - I’m loading an xml file into a textbox. The text is formatted by a style sheet.

This works fine in my browser (it takes a second or two for the css to be applied, which makes it look a bit rubbish, but it works…

However, my friend just sees unformatted text (even after a hard refresh) - as though he’s having trouble finding the stylesheet

Any ideas?