<!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"><head><title>flexbox | block</title> <link href="http://opera.com" rel="author" title="Opera Software" /> <link href="http://www.w3.org/TR/css-flexbox-1/#flex-containers" rel="help" /> <link href="reference/flexbox_empty-ref.xht" rel="match" /> <style> div { background: red; margin-top: -20em; display: flex; } </style> </head><body><div>FAIL</div> </body></html>