<!DOCTYPE html>
<html>
<body>
<div id="div-id" style="height:30px; background-color:gray;">Div Element</div>
<script>
var div_element = document.getElementById("div-id");
var css = window.getComputedStyle(div_element, null).getPropertyValue("background-color");
document.write(css + "<br />");
css = window.getComputedStyle(div_element, null).getPropertyValue("height");
document.write(css);
/*
run:
rgb(128, 128, 128)
30px
*/</script>
</body>
</html>