<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"><html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en"><head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8"/> <title>untitled</title> <style type="text/css" media="screen"> #content { float:left; width:74%; margin-bottom:1%; background-color:#999; } #sidebar { float:right; width:25%; margin-bottom:1%; background-color:#666; } #footer { clear:both; background-color:#333; } body#contact #content { width:100%; } body#contact #sidebar { display:none; } </style> </head><body id="contact"> <div id="content"> <h1>Content</h1> </div> <div id="sidebar"> <h1>Sidebar</h1> </div> <div id="footer"> <h1>Footer</h1> </div></body></html>