how to give box shadow only to bottom code example

Example 1: css box shadow not on bottom

box-shadow: 0px -8px 10px lightgrey;

Example 2: box shadow to make border bottom

-webkit-box-shadow: -2px -1px 15px 7px rgba(0,0,0,0.5);
  -moz-box-shadow: -3px -2px 30px 14px rgba(0,0,0,0.425);
  box-shadow: -4px -3px 45px 21px rgba(0,0,0,0.35);

Example 3: box bottom shadow css

.box-bottom-shadow {
	-webkit-box-shadow: 0 8px 6px -6px black;
	   -moz-box-shadow: 0 8px 6px -6px black;
	        box-shadow: 0 8px 6px -6px black;
}