<!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>CSS Test reference</title> <link rel="author" title="Microsoft" href="http://www.microsoft.com/" /> <link rel="author" title="Florian Rivoal" href="https://florian.rivoal.net/" /> <style type="text/css"> div { height: 1em; margin-bottom: 3px; } #div1 { background-color: black; width: 2em; } #div2 { background-color: blue; width: 3em; } </style> </head> <body> <p>Test passes if the black box below is shorter than the blue box.</p> <div id="div1"></div> <div id="div2"></div> </body> </html>