Make RubyMine autocomplete zurb foundation elements in foo.html.haml?

I'm using a pretty standard configuration of zurb foundation 4 with Rails 4.

When generating views they create foo.html.haml files, which are dynamically injected into the application template. The application template has the direct link to the compiled zurb app.css file, along with any other JS links etc etc

I noticed on prior static projects, when you have a link directly to app.css WebStorm/RubyMine/RandomOtherIDE - if the file title element included app.css, the IDE would autocomplete or offer up available classes that are already compiled out.

What would people suggest to get RubyMine aware of app.css inside foo.html.haml files? (these do not have  a link to app.css)

This would save me many typos / pebkac moments...