1 to 4 values
The margin property can be set to 1 through 4 values, each of which is separated by white spaces.
Depending on the number of values given, they specify:
#elem_1 { /* Margin with four values: */
margin: 5px /* top */
7px /* right */
6px /* bottom */
4px /* left */
}
#elem_2 { /* Margin with three values: */
margin: 5px /* top */
7px /* right, left */
6px /* bottom */
}
#elem_3 { /* Margin with two values */
margin: 5px /* top, bottom */
6px /* left, right */
}
#elem_4 { /* Margin with one value */
margin: 5px /* top, bottom, left, right */
}