Drop shadows to the div using images

I am working on a div which should show a drop shadow at the bottom and right. Here is the link to the html page. I dont know why the classes are not getting applied to the div. Your help is highly appreciated.

Tooltip.html

Here is th开发者_开发问答e image mock-up which shows the Drop shadow affect

Image-mockup

This might help...

You can also drew shadows using css3 in the browser that supported it. Like:

-moz-box-shadow