Check out example codes for "html make box shadow". It will help you in understanding the concepts better.

Code Example 1

box-shadow: 0 20px 20px rgba(0, 0, 0, 0.2), 0px, 0px, 50px rgba(0, 0, 0, 0.2)

Code Example 2

#example1 {
  box-shadow: 10px 10px 8px #888888;
}

Code Example 3

div.card
{

  width: 250px;
  box-shadow: 0 4px 8px 0 rgba(0, 0, 
0, 0.2), 0 6px 20px 0 rgba(0, 0, 0, 0.19);
  text-align: 
center;

}

Code Example 4

box-shadow: 3px 3px 6px 5px #ccc;

or

box-shadow: 0px 5px 17px -7px rgba(0, 0, 0, 0.75);

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