nav bar .active not working

Hello for some reason I can't get the :active a { attribute to work for my navigation bar to work, I tried looking up fixes but nothing is seeming to work.

My HTML:

<nav id="nav">
        <ul>
            <li id='active'><a href="index.html">HOME</a></li>
            <li><a href="services.html">SERVICES</a></li>
            <li><a href="request_fix.html">REQUEST FIX</a></li>
            <li><a href="find_us.html">FIND US</a></li>
            <li><a href="contact_us.html">CONTACT US</a></li>
        </ul>
</nav>

My CSS:

#nav li:active a {
text-shadow: 0 0 1px #808080;
}