divs and h absolute position not displaying correctly firefox IE

[meerkat]

Does anyone have an idea why this is not displaying correctly?

all divs positioned absolute, h1 as well but not showing absolute in Firefox and IE. Works fine with Safari and Chrome. In Firefox, h1 is too low (should be just touching gallery div) and in IE gallery moved up about 4 px and h1 too low. Also h1 is not bold as it should be.

#container{
position:absolute;
margin-left:0px;
margin-top:0px;
width:100%;
height:100%;
}

#header{
position:absolute;
margin-left:0px;
margin-top:0px;
width:100%;
height:100px;
border-bottom:#BEBEBE medium solid;
border-bottom-width:6px;
}

#gallery{
position:absolute;
margin-left:0px;
margin-top:106px;
width:100%;
height: 500px;
background-color:#FFFFFF;
}

#footer{
position:absolute;
margin-left:0px;
margin-top:606px;
height:100%;
width:100%;
border-top:#BEBEBE medium solid;
border-top-width:6px;
text-decoration:none;

}

h1{
position:absolute;
font-family:Arial, Helvetica, sans-serif;
font-size:49px;
margin-left:30px;
margin-top:46px;
text-align:left;
color: #EBEBEB;
font-weight:600;
font-stretch:condensed;
width:200px;
}

Any help much appreciated!

[meerkat]

fixed it! structured it a bit with divs and changed some elements to relative which seems to work now.