Try it Editor

<!DOCTYPE html> 
<html> 
   <head> 
      <title>max-width of element</title> 
      <style> 
         .container { 
         max-width:400px; 
         border:2px solid black; 
         } 
      </style> 
   </head> 
   <body> 
      <div class="container"> 
      <h3>Students Tutorial</h3> 
      <p>The max-width can be defined in length values, like px, cm, etc., or in percent (%) of the containing block, or set to none (this is default. Means that there is no maximum width).
      </p>
	  </div>
   </body> 
</html>