Bootstrap: Fixed-top Issue with Wordpress's Admin Bar

 

Adding an empty space if Admin bar is displayed

Using the Wordpress function to query if the toolbar is displayed, and then create an empty div below the navbar div:

<div class="navbar navbar-inverse navbar-fixed-top">
<?php 
  // Fix menu overlap
  if ( is_admin_bar_showing() ) echo '<div style="min-height: 32px;"></div>'; 
?>
<div class="navbar-inner">

Source: WordPress Admin Bar Overlapping Twitter Bootstrap Navigation