SO fiddle
Test Fiddle mainly for SO Questions
by Nick Craver
HTML
<link rel="stylesheet" href="http://ajax.googleapis.com/ajax/libs/jqueryui/1.8.4/themes/overcast/jquery-ui.css">
<div>Default</div>
<div class="full">Width: 100%, height: 100%</div>
CSS
body { height: 300px; }
div { border: solid 1px #ddd; }
.full { width: 100%; height: 100%; }