I've this fragment of code in my rails app:
<%= link_to "Log out", logout_path, { :title => "Log out", :class => "bannerlink"} %>
It generates following html code:
<a href="/logout" class="bannerlink" title="Log out">Log out</a>

If I open the css file in the RubyMine with the following fragment of css code:

a.bannerlink {
    text-decoration: none;
    color: #fff;
}

the word bannerlink is with warning 'Unused CSS selector'. But the bannerlink is used .... not in html code, but in the erb file.

Environment: Mac OS 10.5.7