Pony.fm/public/templates/content/_layout.html

<ul class="tabs">
    <li ng-class="{active: stateIncludes('content.tracks') || stateIncludes('content.track')}"><a href="/tracks">Tracks</a></li>
    <li ng-class="{active: stateIncludes('content.albums') || stateIncludes('content.album')}"><a href="/albums">Albums</a></li>
    <li ng-class="{active: stateIncludes('content.playlists') || stateIncludes('content.playlist')}"><a href="/playlists">Playlists</a></li>
    <li ng-class="{active: stateIncludes('content.artists') || stateIncludes('content.artist')}"><a href="/artists">Artists</a></li>
</ul>

<ui-view></ui-view>