title: How can i set multiple CSS class from JavaScript
body: <p>I have the following </p>
  
  <p><strong>CSS:</strong></p>
  
  <pre><code>.a { position: absolute; }    
  .a .b { color: red }    
  .a .c { color: green }
  </code></pre>
  
  <p>How can i set the ".a .b" class for element with Java Script?</p>