border-bottom: 2px dashed gray
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta http-equiv="content-type" content="text/html; charset=utf-8" /> <title></title> <style type="text/css" media="Screen"> * .myStyle { border-bottom: 2px dashed gray; } </style> </head> <body> <p> <code>border</code>: <span class="myStyle">Under 6</span> </p> </body> </html>