I am making a CSS navigation bar, which is stored in a folder called 'includes'. Basically what I want is, when a link is clicked, for it to become active. Im linking to this folder with "include('includes/header.php');"

My CSS is:
nav ul li a {
font-size:22px;
color:#fff;
height:67px;
line-height:67px;
text-decoration:none;
min-width:101px;
text-align:center;
float:left;
background: grey;
border-right:1px solid black;}
nav ul li a.current, nav ul li a:hover {padding-bottom:5px;}
The content of header.php is:
<header>
<div class="container">
<nav>
<ul>
<li><a href="index.php">Home</a></li>
<li><a href="services.php">Services</a></li>
<li><a href="#">Blog</a></li>
<li><a href="/forum/index.php">Forums</a></li>
<li><a href="contact.php">Contact</a></li>
<li><a href="#">Account</a></li>
</ul>
</nav>
How do I go about using this method, and having each link made active when clicked?