This is some text in a floating div.
Text text text text text text text text text text text text text text text text text text text text text text text
Well, it's crude, but if you stick the floating DIV into another DIV with the background color the same as the page's background, it ends up covering up the H tag's border and making it look like it stops at the margin of the contained DIV.
h1 { border-bottom: 1px solid #000000; }
div.floatout { float: right; background-color: #ffffff; padding: 0; margin: 0; }
div.floatin { width: 200px; border: 1px dotted #ff0000; margin: 1em; }