p font-size: percentage
<?xml version="1.0" encoding="iso-8859-1"?> <!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 Example</title> <meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1" /> <style type='text/css'> p {font-family:arial; font-size:12pt;} /* percentages */ p.fifty {font-size:50%;} p.hundred {font-size:100%;} p.hundredandfifty {font-size:150%;} </style> </head> <body> <h1>Percentages (relative to 12pt)</h1> <p class="fifty">This percentage is 50%</p> <p class="hundred">This percentage is 100%</p> <p class="hundredandfifty">This percentage is 150%</p> </body> </html>