I have a problem centering div in Firefox, it seems to work fine in all webkit browsers, so I dont really know what I'm doing wrong:

**My CSS:**

```
html {
width: 100%;
height: 100%;
}

body {
position: absolute;
top: 0px;
bottom: 0px;
left: 0px;
right: 0px;
height: 100%;
width: 100%;
}

#Page {
position: absolute;
left: 0px;
right: 0px;
top: 0px;
bottom: 0px;
}

#LoginBackground {
position: absolute;
margin-top: -45%;
margin-left: -35%;
left: 50%;
top: 50%;
width: 70%;
height: 90%;
}

```

**My HTML:**

```
<body>
<div id="Page">
<div id="LoginBackground">
</div>
</div>
</body>

```

Is this a bug within the Gecko engine or am I doing something wrong.