Check out example codes for "how to create polaroid effect in css". It will help you in understanding the concepts better.

Code Example 1

-webkit-box-shadow: 0 4px 6px rgba(0, 0, 0, .3);
-moz-box-shadow: 0 4px 6px rgba(0,0,0,.3);
box-shadow: 0 4px 6px rgba(0,0,0,.3);

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