box shadow only for bottom code example

Example 1: box shadow bottom only

box-shadow: 0 4px 2px -2px gray;

Example 2: box shador of one border css

.myDiv
{
  border: 1px solid #333;
  width: 100px;
  height: 100px;
  box-shadow: 10px -2px 5px 0px #888;
}