As I prefer to use PHP includes to visually clean up my sites, I tend to run into a problem where an active state for buttons or icons is not set. This means that if the header is in an include, and a user lands on the contact page, they’re unable to tell whether a menu option is the one they selected. Problematic, but, here’s a couple of code snippets that worked for me (both in JS):

<script>  $(document).ready(function () {  
var url = window.location;  // Will only work if string in href matches with location  
$('ul.nav a[href="' + url + '"]').parent().addClass('active');

// Will also work for relative and absolute hrefs  
$('ul.nav a').filter(function () {  
return this.href == url;  
}).parent().addClass('active').parent().parent().addClass('active');  });

</script>

The only other step is to define the .active class.

ul.nav li.active {

font-weight:bold;

text-decoration:underline;

}