CSS classes to add to span tags
For easy implementation, labels and badges will simply collapse (via CSS's :empty selector) when no content exists within.
<span class="label label-default">Default</span>
<span class="label label-primary">Important</span>
<span class="label label-success">Success</span>
<span class="label label-warning">Warning</span>
<span class="label label-info">Info</span>
<span class="label label-danger">Danger</span>