The default href with PowerUI is resources:// so you don't need 'Resources/' just "/bootstrapUnity.css". (If you have the .bytes extension added this means you don't need it mentioned in the HTML file, as Unity will 'name' it without .bytes so that .css/.js links work normally..)..

Assuming bootstrapUnity.css.bytes is in the root of a 'resources' folder, try:

The default href with PowerUI is resources:// so you don't need Resources/ just /bootstrapUnity.css.

(If you have the .bytes extension added, this means you don't need it mentioned in the HTML file, as Unity will 'name' it without .bytes so that .css/.js links work normally..)..

Assuming bootstrapUnity.css.bytes is in the root of a 'resources' folder, try: <link href="/bootstrapUnity.css"/>