<!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 | flexcontainer vs generated content</title> <link href="http://opera.com" rel="author" title="Opera Software" /> <link href="http://www.w3.org/TR/css-flexbox-1/#flex-container" rel="help" /> <link href="reference/flexbox_generated-ref.xht" rel="match" /> <style> div { background: #3366cc; display: flex; } div::after, p { content: "xxx"; background: yellow; margin: 1em; width: 200px; height: 2em; } div::after { content: "yyy"; display: block; } </style> </head><body><div> <p>FAIL</p> </div> </body></html>