float left and margin left 34%
<html> <head> <style type='text/css' media='all'> div { background: #aaa; border: 5px solid black; font-size: 200%; padding: 1%; } #div1 { float: left; width: 30%; } #div2 { margin-left: 34%; width: auto; } </style> </head> <body> <div id='div1'> this is a test. </div> <div id='div2'> this is a test. <em>this is a test. </em>this is a test. </div> </body> </html>