CSS3 Bubble

Without borders for better customizablility

HTML

<script src="https://raw.github.com/LeaVerou/prefixfree/master/prefixfree.min.js"></script>
<div id="mapcanvas">asdf</div>

CSS

html,body {width:100%;height:100%;margin:0;padding:0;}

#mapcanvas {
    background:red;display: block;
    position:absolute;
    height:auto;
    bottom:0;
    top:0;
    left:0;
    right:0;
    margin-top:50px;
}