you need to define the class inside the A tag.
<a href="{$http_location}/home.php " class="HeadLine">Home |</a>
<a href="{$http_location}/cart.php " class="HeadLine">Shopping Cart |</a>
<a href="{$http_location}/help.php?section=contactus&mode=update " class="HeadLine">Contact Us</a>