No CSS positioning applied:
CSS positioning: float the dts and give them a width:
dt { width: 10em; float: left; }
dd { margin-left: 10em; }
CSS positioning: position the dts absolutely.
dl { position: relative; }
dl dt { width: 10em; position: absolute; left: 0; }
dl dd { margin-left: 10em; }
(Tested in Mozilla 1.7, Opera 7.5. Fails in NN 4.7)