How does Intellij code inspection decide on selectors from .css files?

I have a css file in which there's a selector for class App-logo

.App-logo {
  animation: App-logo-spin infinite 20s linear;
  height: 75px;
}

The file is in resources/public directory.

In the resources directory, there's a file called testform.vtl (a velocity file), in which the following lines appear:

      <div class="App-header" >
         <img src="favicon.png"  class="App-logo pull-left" alt="logo"  />
         <h2>Data Insight - Known Issues Console </h2>
      </div>

When I run code inspection in Intellij, it gives me the warning Selector app-logo is never used. Why is this? Is there a configuration that I can use in Intellij to cause it to look at these vtl files (if this is actually the problem)?

The IDE only looks for CSS selector usages in stylesheets and HTML files/fragments; it won't inspect plain text files and files of unknown type. I've just checked - CSS usages are correctly found in Velocity templates:

Make sure to add *.vtl pattern to Velocity Template file type in Settings | Editor | File Types