title: What is the most efficient way to give the active page's menu item a "selected" id to change the CSS?
body: <p>Lets say I have 5 pages: A, B, C, D, and E. I also have a horizontal menu, and each item has a light gray background.</p>
  
  <p>Each menu item has a:hover that gives it a medium-gray background, but I want the active page to have a black background, so I define</p>
  
  <pre><code>#black {
      background-color: #000;
  }
  </code></pre>
  
  <p>Now when the user is on B.php, I want the B menu item to carry the #black id. What is the best way of doing this?</p>