title: How to make a .nav-link inactive?
body: <p>I am using a Bootstrap <code>nav-bar</code> for a wizard progress indicator. I want to make sure that steps of the wizard which have not been visited yet are not clickable. I would like them to appear in the <code>nav-bar</code>, but have them be greyed out and the links be disabled.</p>
  <p>Can this be done in the Bootstrap <code>nav-bar</code>?</p>