Can't attach an external stylesheet

Can't attach an external stylesheet

Hi, whenever I try to attach an external stylesheet to my wiki via 'workspace' > 'settings' > 'customisation' the stylesheet is not picked up when the wiki is viewed in my browser(s).  I did some digging using Chrome's browser development tools and noticed that the stylesheet is not getting loaded because of the following error:

"Resource interpreted as stylesheet but transferred with MIME type text/plain"

Seems to me this is something in the way the zoho server is serving this file... can someone shed any light on what the problem might be?