Application theme (styles.css) not found in filesystem, but it's there!

Hi, I’ve created a custom styles.css sheet for my Vaadin application (CIPS), located in VAADIN/themes/CIPS/, but whenever I try to launch my application, I get this error message:

However, the file is right there on that path! It even shows up in the project tree on the right side of my Eclipse IDE, but for some reason it still gives me that error message. I’ve tried everything from editing my web.xml file to map the servlet to the /* root as well as /VAADIN/*, to adding the directory as a jar file, but nothing has worked.

If anyone has any insight it would be much appreciated.
Thanks!