Minor CSS issue

Question

I am new to the designing/programming world so I am sure the issue is easy to solve. I am trying to add the moz-box-shadow effect to my header. But as soon as I add that component, the header which is taking up space horizontally shortens up. I want the header to be like Twitter's, where they use a shadow effect.

#header {
    background-color: #990000;
    width:101.3%;
    margin-left:-8px;
    margin-top:-8px;
    height:40px;
    -moz-box-shadow: 1px 1px 10px #D7D7D7;
}

Also, the way i have set the width is it likely going to create cross browser issues?

Answer 1

Here's a version similar to what Twitter has:
This is Twitter's version, more or less:

Live Demo (edit)

HTML:

<div id="top-fixed">
    <div id="top-bar"></div>
</div>

CSS:

html, body {
    margin: 0; padding: 0
}
body {
    padding-top: 50px;
    background: #c0deed
}
#top-fixed {
    position: fixed;
    left: 0;
    right: 0;
    top: 0;
    z-index: 1000;
}
#top-bar {
    height: 40px;
    width: 100%;

    background-color:#00a0d1;
    background-image:-webkit-gradient(linear,0 0,0 100%,from(#00a0d1),to(#008db8));
    background-image:-moz-linear-gradient(#00a0d1,#008db8);
    filter:progid:DXImageTransform.Microsoft.gradient(startColorstr='#00a0d1',endColorstr='#008db8');
    -ms-filter:"progid:DXImageTransform.Microsoft.gradient(startColorstr='#00a0d1',endColorstr='#008db8')";

    -webkit-box-shadow: 0 1px 3px rgba(0, 0, 0, 0.25);
    -moz-box-shadow: 0 1px 3px rgba(0, 0, 0, 0.25);
    box-shadow: 0 1px 3px rgba(0, 0, 0, 0.25);
}