<!DOCTYPE HTML>
<title>outline goes around overflow, floats</title>
<style>
html, body { margin: 0; padding: 0; border: none }
html { overflow:hidden /* avoid second reflow for scrollbars */ }
body > div { margin: 100px; outline: 2px solid blue }
body > div > div { float: left; width: 100px; height: 100px }
</style>
<body>
<div><div></div></div>