<!doctype html>
<html>

Will be green if the relative positioned table cell properly acts as a containing block.

<table style="border:1px solid black" cellspacing=100 cellpadding=0>
<tr><td style="position:relative;width:100px;height:100px;background-color:red">
<div style="position:absolute;left:0;top:0;width:100px;height:100px;background-color:green">