The bottom CSS property participates in specifying the vertical position of a positioned element. It has no effect on non-positioned elements.

/* <length> values */
bottom: 3px;
bottom: 2.4em;

/* <percentage>s of the height of the containing block */
bottom: 10%;

/* Keyword value */
bottom: auto;

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

The effect of bottom depends on how the element is positioned (i.e., the value of the position property):

  • When position is set to absolute or fixed, the bottom property specifies the distance between the element's bottom edge and the bottom edge of its containing block.
  • When position is set to relative, the bottom property specifies the distance the element's bottom edge is moved above its normal position.
  • When position is set to sticky, the bottom property behaves like its position is relative when the element is inside the viewport, and like its position is fixed when it is outside.
  • When position is set to static, the bottom property has no effect.

When both top and bottom are specified, and height is unspecified or either auto or 100%, both the top and bottom distances are respected. In all other situations, if height is constrained in any way, the top property takes precedence and the bottom property is ignored.

Initial valueauto
Applies topositioned elements
Inheritedno
Percentagesrefer to the height of the containing block
Mediavisual
Computed valueif specified as a length, the corresponding absolute length; if specified as a percentage, the specified value; otherwise, auto
Animation typea length, percentage or calc();
Canonical orderthe unique non-ambiguous order defined by the formal grammar

Syntax

Values

<length>
A negative, null, or positive <length> that represents:
  • for absolutely positioned elements, the distance to the bottom edge of the containing block.
  • for relatively positioned elements, the distance that the element is moved above its normal position.
<percentage>
A <percentage> of the containing block's height.
auto
Specifies that:
  • for absolutely positioned elements, the position of the element is based on the top property, while height: auto is treated as a height based on the content.
  • for relatively positioned elements, the distance of the element from its normal position is based on the top property, or if top is also auto, the element is not moved vertically at all.
inherit
Specifies that the value is the same as the computed value from its parent element (which might not be its containing block). This computed value is then handled as if it were a <length>, <percentage>, or the auto keyword.

Formal syntax

<length> | <percentage> | auto

Example

This example demonstrates the difference in behavior of the bottom property, when position is absolute versus fixed.

HTML

<p>This<br>is<br>some<br>tall,<br>tall,<br>tall,<br>tall,<br>tall<br>content.</p>
<div class="fixed"><p>Fixed</p></div>
<div class="absolute"><p>Absolute</p></div>

CSS

p {
  font-size: 30px;
  line-height: 2em;
}

div {
  width: 48%;
  text-align: center;
  background: rgba(55,55,55,.2);
  border: 1px solid blue;
}

.absolute {
  position: absolute;
  bottom: 0;
  left: 0;
}

.fixed {
  position: fixed;
  bottom: 0;
  right: 0;
}

Result

Specifications

Specification Status Comment
CSS Transitions
The definition of 'bottom' in that specification.
Working Draft Defines bottom as animatable.
CSS Positioned Layout Module Level 3
The definition of 'bottom' in that specification.
Working Draft Adds behavior for sticky positioning.
CSS Level 2 (Revision 1)
The definition of 'bottom' in that specification.
Recommendation Initial definition.

Browser compatibility

FeatureChromeEdgeFirefoxInternet ExplorerOperaSafari
Basic support1 Yes15161
FeatureAndroid webviewChrome for AndroidEdge mobileFirefox for AndroidIE mobileOpera AndroidiOS Safari
Basic support Yes Yes Yes4 Yes Yes Yes

1. In Internet Explorer versions before 7, when both top and bottom are specified, the element position is overconstrained and the top property has precedence; the computed value of bottom is set to -top, while its specified value is ignored.

See also