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; /* <percentages> 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 toabsolute
orfixed
, thebottom
property specifies the distance between the element's bottom edge and the bottom edge of its containing block. - When
position
is set torelative
, thebottom
property specifies the distance the element's bottom edge is moved above its normal position. - When
position
is set tosticky
, thebottom
property behaves like its position isrelative
when the element is inside the viewport, and like its position isfixed
when it is outside. - When
position
is set tostatic
, thebottom
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 value | auto |
---|---|
Applies to | positioned elements |
Inherited | no |
Percentages | refer to the height of the containing block |
Media | visual |
Computed value | if specified as a length, the corresponding absolute length; if specified as a percentage, the specified value; otherwise, auto |
Animation type | a length, percentage or calc(); |
Canonical order | the 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, used as described in the summary. auto
- Specifies that:
- for absolutely positioned elements, the position of the element is based on the
top
property, whileheight: 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 iftop
is alsoauto
, the element is not moved vertically at all.
- for absolutely positioned elements, the position of the element is based on the
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 theauto
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 Level 2 (Revision 1) The definition of 'bottom' in that specification. |
Recommendation | Initial definition. |
Browser compatibility
Feature | Chrome | Edge | Firefox (Gecko) | Internet Explorer | Opera | Safari (WebKit) |
---|---|---|---|---|---|---|
Basic support | 1.0 | (Yes) | 1.0 (1.7 or earlier) | 5[1] | 6 | 1.0 (85) |
Feature | Android | Edge | Firefox Mobile (Gecko) | IE Phone | Opera Mobile | Safari Mobile |
---|---|---|---|---|---|---|
Basic support | ? | (Yes) | 1.0 (1.9.2) | ? | ? | ? |
[1] In Internet Explorer versions before 7.0, when both top
and bottom
are specified, the element position is over-constrained and the top
property has precedence. In that case the computed value of bottom
is set to -top
, while its specified value is ignored.