#mm .rollOver {
height: 165px; /* IE 6 & bellow */
}
html>body #mm .rollOver {
height: 163px; /* FF & Others */
}
*:first-child+html #mm .rollOver {
height: 165px !important; /* #%@#%(! IE 7 */
}
p.style { color:red; } /* IE7 */
* html p.style { color:blue; } /* Other IE */
*|html p.style { color:pink; } /* FF, Opera, Konqueror, Safari */

#ie7-hook-id div[class^="target-class"] { background: #ff0000; }
div#ie7-hook-id .target-class { background: #0000ff; }

* div[class^="ie7-target-class"] { background: #ff0000; }
body .ie7-target-class { background: #0000ff; }

Valid CSS Selectors

* html {} /* IE 6 and below */
*:first-child+html {} * html {} /* IE 7 and below */
*:first-child+html {} /* IE 7 only */
html>body {} /* IE 7 and modern browsers only */
html>/**/body {} /* Modern browsers only (not IE 7) */
html:first-child {} /* Recent Opera versions 9 and below */

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When Explorer and Opera parsing the CSS file, encounter the JavaScript and execute it. Browsers execute it only once, though, so if you’d repeat the background-image: etc for another class or id, you still see one alert only.

So Lets Try this:

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#Example {
border: 1px solid #000000;
padding: 10px;
background-image: url('javascript:alert(\'It works\');')

or

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background-image: url('javascript:alert('It works');')