element()

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.

Syntax

element(id)

where:

id

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

Formal syntax

<element()> = 
 element( <id-selector> ) 

<id-selector> = 
 <hash-token> 

Examples

These examples work 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 id="target-box">
 <p>This box uses the element with the #my-background ID as its background!</p>
</div>
<div id="background-container">
 <div id="my-background">
 <p>This text is part of the background. Cool, huh?</p>
 </div>
</div>

#target-box {
 width: 400px;
 height: 400px;
 background: -moz-element(#my-background) no-repeat;
}
#background-container {
 overflow: hidden;
 height: 0;
}
#my-background {
 width: 1024px;
 height: 1024px;
 background-image: linear-gradient(to right, red, orange, yellow, white);
}
#my-background p {
 transform-origin: 0 0;
 rotate: 45deg;
 color: white;
}

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

Page Preview

This example based on Vincent De Oliveira's creates a preview of the <div id="css-source"> inside <div id="css-result">.

HTML

<div id="css-source">
 <h1>Page Preview</h1>
</div>
<div id="css-result"></div>

CSS

#css-result {
 background: -moz-element(#css-source) no-repeat;
 width: 256px;
 height: 32px;
 background-size: 80%;
 border: dashed;
}

Result

Specifications

Browser compatibility

See also

• image()
• image-set()
• <image>
• <gradient>
• cross-fade()
• document.mozSetImageElement()