A simple shadow stack with only six settings. You need this stack if you want to make your web designs "less flat".
What's great about CSS box shadows is that they are supported by all mainstream web browsers and do not require images.
Think back ten years ago, and remember the late-night trauma of diligently painting all those shadow effects by hand in Photoshop, and the tortuous process of exporting each one as a JPG, and the additional pain of trying to make it all line-up correctly in a webpage. CSS Box shadows put an end to this craziness!
Alongside the obvious page loading speed advantage of non-image shadow effects, CSS box shadows bend and flex to fit the content placed within.