1<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> 2<html> 3<head> 4<style> 5body { margin: 0px; } 6.outer { 7 margin: -100px; 8 width: 400px; 9 height: 500px; 10 background-color: green; 11} 12.outer:hover { 13 background-color: red; 14} 15.inner { 16 visibility: hidden; 17 width: 100%; 18 height: 50%; 19 background-color: cyan; 20} 21</style> 22</head> 23 24<body> 25<div class="outer" 26 onmouseover="firstChild.style.visibility='visible'" 27 onmouseout="firstChild.style.visibility='hidden'"><div class="inner"></div></div> 28</body> 29</html> 30