Ragazzi vi posto questo stile css da me creato:

#container {

margin-right: auto;
margin-left: auto;
width: 800px;
position: relative;
}
body {
margin-top: 0px;
margin-bottom: 0px;
background-image: url('images/sfondo.png');
}

#contenitore{
width: 800px;
height: 100%;
align: center;
}

a{
color: white;
text-decoration: none;
}

#header {
width: 800px;
position: relative;
top: 0px;
left: 0px;
align: center;
}
#headerlaterale{
width: 238;
height: 103;
align: left;
position: relative;
top: 0px;
left: 0px;
float: left;
}
#headercentrale{
width: 464px;
position: relative;
float: left;
}
#headerdestro{
width: 98px;
position: relative;
float: right;
}
#headerbarra{
position: relative;
float: left;
margin-top: -1px;
}

#contenitorecentrale{
width: 800px;
position: relative;
top: 0px;
left: 0px;
align: center;
}
#primariga{
width: 800px;
height: 37px;
position: relative;
}
#secondariga{
width: 800px;
height: 100px;
position: relative;
}
#terzariga{
width: 800px;
hwight: 37px;
position: relative;
}

questo è il codice html che richiama lo stile css

<div id="contenitore">
<div id="container">
<div id="header">
[img]esteticasliced_01.png[/img]</div>
<div id="headerlaterale">
[img]esteticasliced_02.png[/img]</div>
<div id="headercentrale">
<object classid="clsid27CDB6E-AE6D-11CF-96B8-444553540000" id="obj1" codebase="http://download.macromedia.com/pub/shockwave/cabs/flash/swflash.cab#version=6,0,40,0" border="0" width="464" height="21">
<param name="movie" value="menuestaetica.swf">
<param name="quality" value="High">
<embed src="menuestaetica.swf" pluginspage="http://www.macromedia.com/go/getflashplayer" type="application/x-shockwave-flash" name="obj1" width="464" height="21" quality="High"></object>
</div>
<div id="headerdestro">
[img]esteticasliced_04.png[/img]</div>
<div id="headerbarra">
[img]esteticasliced_05.png[/img] </div>
</div>



</div>

in internet explorer si vede bene. In firefox me lo da tutto sfalsato.. come mai?