margin: 5%;                 /* All sides: 5% margin */

margin: 10px;               /* All sides: 10px margin */

margin: 1.6em 20px;         /* top and bottom: 1.6em margin */
                            /* left and right: 20px margin */

margin: 10px 3% -1em;       /* top:            10px margin */
                            /* left and right: 3% margin   */
                            /* bottom:         -1em margin */

margin: 10px 3px 30px 5px;  /* top:    10px margin */
                            /* right:  3px margin  */
                            /* bottom: 30px margin */
                            /* left:   5px margin  */

margin: 2em auto;           /* top and bottom: 2em margin   */
                            /* Box is horizontally centered */

margin: auto;               /* top and bottom: 0 margin     */
                            /* Box is horizontally centered */