CSS e FIREFOX/IE

<style type="text/css" media="screen">

#sliderContent {
    width: 660px; /* important to be same as image width or wider */
    position: absolute;    
    margin-top: 0px;    
    [IF lte IE 7.0] margin-left: 0px;  
    [IF IE 8.0]  margin-left: -40px;
    [IF Gecko]  margin-left: -40px;    
}
</style>

<!--[IF lte IE 7.0] >
<style type="text/css" media="screen">

#sliderContent {
    width: 660px; /* important to be same as image width or wider */
    position: absolute;    
    margin-top: 0px;    
    margin-left: 0px;    
}
</style>
<!--[end if]>

<!-- [IF IE 8.0]  >
<style type="text/css" media="screen">
#sliderContent {
    width: 660px; /* important to be same as image width or wider */
    position: absolute;    
    margin-top: 0px;       
    margin-left: -40px;
}
</style>
<!--[end if]>


.... ecc