.popover-title {
    color: blue;
    font-size: 15px;
}
.popover-content {
    color: red;
    font-size: 10px;
}

.popover
    |_  .popover-title
    |_  .popover-content

<div id="my-container">
  <a href="#" id="popover-trigger">Popover This!</a>
</div>

<style>
  .popover-title { color: green; }  /* default title color for all popovers */

  #my-container .popover-title { color: red; }  /* specific popover title color */
</style>

$("#myElement").popover({
  template: '<div class="popover my-specific-popover" role="tooltip">...'
});