<root> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <style type="text/css"> root, html { display: block; margin: 0; padding: 0; } root { margin: 20px 0; } html { background-color: green; margin: 10px 0; height: 100px; } </style> </head> </html> </root>
