margin - CSS: Cascading Style Sheets 编辑

The margin CSS property sets the margin area on all four sides of an element. It is a shorthand for margin-top, margin-right, margin-bottom, and margin-left.

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The top and bottom margins have no effect on non-replaced inline elements, such as <span> or <code>.

Note: Margins create extra space around an element. In contrast, padding creates extra space within an element.

Syntax

/* Apply to all four sides */
margin: 1em;
margin: -3px;

/* vertical | horizontal */
margin: 5% auto;

/* top | horizontal | bottom */
margin: 1em auto 2em;

/* top | right | bottom | left */
margin: 2px 1em 0 auto;

/* Global values */
margin: inherit;
margin: initial;
margin: unset;

The margin property may be specified using one, two, three, or four values. Each value is a <length>, a <percentage>, or the keyword auto. Negative values draw the element closer to its neighbors than it would be by default.

• When one value is specified, it applies the same margin to all four sides.
• When two values are specified, the first margin applies to the top and bottom, the second to the left and right.
• When three values are specified, the first margin applies to the top, the second to the right and left, the third to the bottom.
• When four values are specified, the margins apply to the top, right, bottom, and left in that order (clockwise).

Values

<length>

The size of the margin as a fixed value.

<percentage>

The size of the margin as a percentage, relative to the width of the containing block.

auto

The browser selects a suitable margin to use. For example, in certain cases this value can be used to center an element.

Formal syntax

[ <length> | <percentage> | auto ]{1,4}

Examples

Simple example

HTML

<div class="center">This element is centered.</div>

<div class="outside">This element is positioned outside of its container.</div>

CSS

.center {
  margin: auto;
  background: lime;
  width: 66%;
}

.outside {
  margin: 3rem 0 0 -3rem;
  background: cyan;
  width: 66%;
}

More examples

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 */

Notes

Horizontal centering

To center something horizontally in modern browsers, you can use display: flex;justify-content: center; .

However, in older browsers like IE8-9 that do not support Flexible Box Layout, these are not available. In order to center an element inside its parent, use margin: 0 auto;.

Margin collapsing

Elements' top and bottom margins are sometimes collapsed into a single margin that is equal to the larger of the two margins. See Mastering margin collapsing for more information.

Specifications

Browser compatibility

BCD tables only load in the browser

See also

• Introduction to the CSS basic box model
• Margin collapsing
• margin-top, margin-right, margin-bottom, and margin-left
• The mapped logical properties: margin-block-start, margin-block-end, margin-inline-start, and margin-inline-end and the shorthands margin-block and margin-inline