mozilla

position

Summary

The position CSS property chooses alternative rules for positioning elements, designed to be useful for scripted animation effects.

A positioned element is an element whose computed position property is relative, absolute, fixed or sticky.

relatively positioned element is an element whose computed position property is relative.

An absolutely positioned element is an element whose computed position property is absolute or fixed.

A stickily positioned element is an element whose computed position property is sticky.

The top, right, bottom, and left properties specify the position of positioned elements.

Syntax

/* Keyword values */
position: static;
position: relative;
position: absolute;
position: fixed;
position: sticky;

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

Values

static
This keyword lets the element use the normal behavior, that is it is laid out in its current position in the flow.  The top, right, bottom, left and z-index properties do not apply.
relative
This keyword lays out all elements as though the element were not positioned, and then adjust the element's position, without changing layout (and thus leaving a gap for the element where it would have been had it not been positioned). The effect of position:relative on table-*-group, table-row, table-column, table-cell, and table-caption elements is undefined.
absolute
Do not leave space for the element. Instead, position it at a specified position relative to its closest positioned ancestor or to the containing block. Absolutely positioned boxes can have margins, they do not collapse with any other margins.
fixed
Do not leave space for the element. Instead, position it at a specified position relative to the screen's viewport and don't move it when scrolled. When printing, position it at that fixed position on every page.
sticky 
The box position is calculated according to the normal flow (this is called the position in normal flow). Then the box is offset relative to its flow root and containing block and in all cases, including table elements, does not affect the position of any following boxes. When a box B is stickily positioned, the position of the following box is calculated as though B were not offset. The effect of ‘position: sticky’ on table elements is the same as for ‘position: relative’.

Formal syntax

static | relative | absolute | sticky | fixed

Examples

Relative positioning

To position an element relatively 20px from the top and left of its normal position, the following CSS is used.

#two { position: relative; top: 20px; left: 20px; }

Note how the other elements are displayed as if "Two" were in its normal position and taking up space.

Absolute positioning

Elements that are positioned relatively are still considered to be in the normal flow of elements in the document. In contrast, an element that is positioned absolutely is taken out of the flow and thus takes up no space when placing other elements. The absolutely positioned element is positioned relative to nearest positioned ancestor. If a positioned ancestor doesn't exist, the initial container is used.

In the example below, the ancestor div (box One) is positioned relative (so it becomes the nearest positioned ancestor) and box Two is positioned absolutely:

#one { position: relative; width: 500px; }
#two { position: absolute; top: 20px; left: 20px; }

If box One had not been positioned relative, it would not be the nearest positioned ancestor, and so box Two would have appeared relative to the upper left corner of the outer box instead.

Fixed positioning

Fixed positioning is similar to absolute positioning, with the exception that the element's containing block is the viewport. This is often used to create a floating element that stays in the same position even after scrolling the page. In the example below the "One" box is fixed 80px from the top of the page and 20px from the left:

#one { position: fixed; top: 80px; left: 20px; }

When viewing the top of the page, the position box appears in the upper left, and after scrolling, it remains in the same place relative to the viewport:

fixed-1.png

fixed-2.png

Sticky positioning

Sticky positioning is a hybrid of relative and fixed positioning.  The element is treated as relative positioned until it crosses a specified threshold, at which point it is treated as fixed positioned.  For instance:

#one { position: sticky; top: 10px; }
will behave just like a relatively positioned element until the viewport scrolls such that the element would be less than 10px from the top.  Then, it will be fixed to 10px from the top until the viewport is scrolled back past this threshold.
 
Sticky positioning is commonly used for the headings in an alphabetized listing.  The B heading will appear just below the items that begin with A until they are scrolled offscreen.  Rather than sliding offscreen with the rest of the content, the B heading will then remain fixed to the top of the viewport until all the B items have scrolled offscreen, at which point it will be covered up by the C heading.
 
 
You must specify a threshold with at least one of top, right, bottom, or left for sticky positioning to behave as expected.  Otherwise, it will be indistinguishable from relative positioning.
 

Notes

For relatively positioned elements, the top or bottom property specifies the vertical offset from the normal position and the left or right property specifies the horizontal offset.

For absolutely positioned elements, the top, right, bottom, and left properties specify offsets from the edge of the element's containing block (what the element is positioned relative to). The margin of the element is then positioned inside these offsets.

Most of the time, absolutely positioned elements have auto values of height and width computed to fit the contents of the element. However, non-replaced absolutely positioned elements can be made to fill the available space by specifying (as other than auto) both top and bottom and leaving height unspecified (that is, auto). Likewise for left, right, and width.

Except for the case just described of absolutely positioned elements filling the available space:

  • If both top and bottom are specified (technically, not auto), top wins.
  • If both left and right are specified, left wins when direction is ltr (English, horizontal Japanese, etc.) and right wins when direction is rtl (Persian, Arabic, Hebrew, etc.).

Specifications

Specification Status Comment
CSS Level 2 (Revision 1)
The definition of 'position' in that specification.
Recommendation  
CSS Positioned Layout Module Level 3
The definition of 'position' in that specification.
Working Draft Adds sticky property value

Browser compatibility

Feature Chrome Firefox (Gecko) Internet Explorer Opera Safari (WebKit)
Basic support 1.0 1.0 (1.0) [1] 4.0 [3] 4.0 1.0 (85)
fixed value 1.0 1.0 (1.0) 7.0 4.0 1.0 (85)
sticky value ? 32 (32.0)bug 916315 [2] ? ? 6.1 -webkit-
Feature Android Firefox Mobile (Gecko) IE Phone Opera Mobile Safari Mobile
Basic support ? 1.0 (1.0) [1] ? ? iOS 6.1 -webkit-

[1] Since Firefox 30, Gecko allows <tr>, <thead>, and  <tfoot> elements with a position: relative; style to act as absolute positioning containers. This means that a position: absolute; styled element inside the table can be positioned relative to these elements. In other browsers and in older versions of Firefox, setting position: relative; on a table row or row group has no effect. Firefox helps developers transition to the new behavior and detect any rendering issues it may cause on their sites by printing a warning to the JavaScript console if you use this feature:

Relative positioning of table rows and row groups is now supported. This site may need to be updated because it may depend on this feature having no effect.

[2 ] Sticky positioning will only work in Firefox 26 to Firefox 31, included, when the about:config preference layout.css.sticky.enabled is set to true. From Firefox 27 to 31, it was the default value for Nightly and Aurora versions of the browser.

[3] In Internet Explorer, fixed positioning doesn't work if the document is in quirks mode.

See also