<!DOCTYPE html> <html> <head> <style type="text/css"> .separator { height: 20px; background-color: green; } #parent { margin-top: 10px; margin-bottom: 30px; } #child { margin-top: 20px; margin-bottom: 40px; } </style> </head> <body> <div class="separator"></div> <div id="parent"> <div id="child"></div> </div> <div class="separator"></div> </body> </html>