how does box shadow works in css code example

Example 1: css box shadow

/* offset-x | offset-y | blur-radius | spread-radius | color */
box-shadow: 2px 2px 2px 1px rgba(0, 0, 0, 0.2);

Example 2: css box shadow

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

Example 3: box-shadow css

/* Keyword values */
box-shadow: none;

/* offset-x | offset-y | color */
box-shadow: 60px -16px teal;

/* offset-x | offset-y | blur-radius | color */
box-shadow: 10px 5px 5px black;

/* offset-x | offset-y | blur-radius | spread-radius | color */
box-shadow: 2px 2px 2px 1px rgba(0, 0, 0, 0.2);

/* inset | offset-x | offset-y | color */
box-shadow: inset 5em 1em gold;

/* Any number of shadows, separated by commas */
box-shadow: 3px 3px red, -1em 0 0.4em olive;

/* Global keywords */
box-shadow: inherit;
box-shadow: initial;
box-shadow: unset;

Example 4: box-shadow

blockquote {
  padding: 20px;
  box-shadow: 
       inset 0 -3em 3em rgba(0,0,0,0.1), 
             0 0  0 2px rgb(255,255,255),
             0.3em 0.3em 1em rgba(0,0,0,0.3);
}