To style the few paragraphs belonging to the double-space class with a bottom margin of 2 ems using *.double-space{margin-bottom:2em;}.
<!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></title> <style type="text/css"> *.double-space{ margin-bottom:2em; } </style> </head> <body> <h2 class="double-space">This is a header this is a test. this is a test. this is a test. this is a test. this is a test. this is a test. this is a test. this is a test. this is a test. this is a test. this is a test. this is a test. </h2> <p class="double-space">This is a text.</p> <p>This is a text.</p> </body> </html>