id

by oraclepadawan

HTML

<html>
  <body>
     <style>
        #caja {
            border: solid 1px black;
            width: 50%;
            background-color: blueviolet;
            min-height: 40px;
        }
</style>
 
<div id="caja">
 
</div>
  </body>
</html>