<!DOCTYPE html> <html> <head> <!-- specifying all heights in em units so that large font sizes don't disrupt relationships; everything will scale together --> <style type="text/css"> #parent { width: 200px; background-color: lightgreen; } #inline-block1, #inline-block2 { height: 2em; background-color: green; } #margin { height: 2em; } </style> </head> <body> <div id="parent"> <div id="inline-block1"></div> <div id="margin"></div> <div id="inline-block2"></div> </div> </body> </html>