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.
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
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>
<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; rotate: 45deg; color:white;">
This text is part of the background. Cool, huh?
</p>
</div>
</div>
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!".
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;
}