The element() CSS function defines an <image> value generated from an arbitrary HTML element. This image is live, meaning that if the HTML element is changed, the CSS properties using the resulting value are automatically updated.

A particularly useful scenario for using this would be to render an image in an HTML <canvas> element, then use that as a background.

On Gecko browsers, you can use the non-standard document.mozSetImageElement() method to change the element being used as the background for a given CSS background element.


element( id )


The ID of an element to use as the background, specified using the HTML attribute #id on the element.


These examples can be viewed live in builds of Firefox that support -moz-element().

A somewhat realistic example

This example uses a hidden <div> as a background. The background element uses a gradient, but also includes text that is rendered as part of the background.

<div style="width:400px; height:400px; background:-moz-element(#myBackground1) no-repeat;">
  <p>This box uses the element with the #myBackground1 ID as its background!</p>

<div style="overflow:hidden; height:0;">
  <div id="myBackground1" style="width:1024px; height:1024px; background-image: linear-gradient(to right, red, orange, yellow, white);">
  <p style="transform-origin:0 0; transform: rotate(45deg); color:white;">This text is part of the background. Cool, huh?</p>

The <div> element with the ID "myBackground1" is used as the background for the content including the paragraph "This box uses the element with the #myBackground1 ID as its background!".


A somewhat more bizarre example

This example uses a hidden <button> element in a repeating pattern as its background. This demonstrates that you can use arbitrary elements as background, but doesn't necessarily demonstrate good design practices.

<div style="width:400px; height:100px; background:-moz-element(#myBackground2);">

<div style="overflow:hidden; height:0;">
  <button id="myBackground2" type="button">Evil button!</button>



Specification Status Comment
CSS Image Values and Replaced Content Level 4 Working Draft Actually now deferred to CSS4.

Browser compatibility

Feature Firefox (Gecko) Chrome Internet Explorer Opera Safari
Basic support 4.0 (2.0) [*] -moz 未实现 未实现 未实现 未实现
Feature Firefox Mobile (Gecko) Android IE Phone Opera Mobile Safari Mobile
Basic support 4.0 (2.0) [*] -moz 未实现 未实现 未实现 未实现

[*] Usage limited to the background and background-image CSS properties.

See also


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