Please Identify Mouse Hover Effect

I need help. Please open below url. In this url, you will see 3 boxes above footer. On any of them box there is a mouse hover effect. Please tell me how can I create this myself? Is this CSS3?

http://thepaintdrop.com/

Code (markup):

 

You are looking for inner shadow effect. Here is a tutorial I picked up from Google:

http://designshack.net/articles/css/inner-shadows-in-css-images-text-and-beyond/

 

.box:hover {
inset 0 0 50px rgba(0,0,0,0.75);
}

Code (CSS):

<div class="box">

</div>

HTML: