Why does GOOD VERSION, below, work perfectly, but the BAD VERSION fails (all browsers)? The only difference is the order of TOPIMAGE and BOTTOMIMAGE in the 2nd IMAGEBUTTON. How can I adjust my CSS so both versions work? GOOD VERSION <style> a.IMAGEBUTTON img.TOPIMAGE { z-index:1; position:absolute; } a.IMAGEBUTTON:hover img.TOPIMAGE { filter:alpha(opacity=0); -moz-opacity:0.0; -khtml-opacity: 0.0; opacity: 0.0; } a.IMAGEBUTTON img {width:150px; } </style> <a class="IMAGEBUTTON" href="http://google.com" > <img class="TOPIMAGE" src="pics\pic2.jpg" /> <img class="BOTTOMIMAGE" src="pics\pic1.png" /> </a> <a class="IMAGEBUTTON" href="http://google.com" > <img class="TOPIMAGE" src="pics\pic2.jpg" /> <img class="BOTTOMIMAGE" src="pics\pic1.png" /> </a> Code (markup): BAD VERSION <style> a.IMAGEBUTTON img.TOPIMAGE { z-index:1; position:absolute; } a.IMAGEBUTTON:hover img.TOPIMAGE { filter:alpha(opacity=0); -moz-opacity:0.0; -khtml-opacity: 0.0; opacity: 0.0; } a.IMAGEBUTTON img {width:150px; } </style> <a class="IMAGEBUTTON" href="http://google.com" > <img class="TOPIMAGE" src="pics\pic2.jpg" /> <img class="BOTTOMIMAGE" src="pics\pic1.png" /> </a> <a class="IMAGEBUTTON" href="http://google.com" > <img class="BOTTOMIMAGE" src="pics\pic1.png" /> <img class="TOPIMAGE" src="pics\pic2.jpg" /> </a> Code (markup): THANKS