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14. Margins, Borders, and Padding
14-1 Margin(邊界)
margin-top: /*some value*/
margin-right: /*some value*/
margin-bottom: /*some value*/
margin-left: /*some-value*/
margin: 1px 2px 3px 4px;
will set a top margin of 1 pixel, a right margin of 2, a bottom of 3, and a left of 4.(順時針)