This feature is non-standard and is not on a standards track. Do not use it on production sites facing the Web: it will not work for every user. There may also be large incompatibilities between implementations and the behavior may change in the future.

The -moz-context-properties property can be used within privileged contexts in Firefox to share the values of specified properties of the element with a child SVG image.

If you reference an SVG image in a webpage (such as with the <img> element or as a background image), the SVG image can coordinate with the embedding element (its context) to have the image adopt property values set on the embedding element. To do this the embedding element needs to list the properties that are to be made available to the image by listing them as values of the -moz-context-properties property, and the image needs to opt in to using those properties by using values such as the context-fill value.


/* Keyword values */
-moz-context-properties: fill;
-moz-context-properties: fill, stroke;

/* Global values */
-moz-context-properties: inherit;
-moz-context-properties: initial;
-moz-context-properties: unset;


Expose the fill value set on the image to the embedded SVG.
Expose the stroke value set on the image to the embedded SVG.
Expose the fill-opacity value set on the image to the embedded SVG.
Expose the stoke-opacity value set on the image to the embedded SVG.

Formal definition

Initial valuenone
Applies toAny element that can have an image applied to it, for example as a background-image, border-image, or list-style-image.
Computed valueas specified
Animation typediscrete

Formal syntax

none | [ fill | fill-opacity | stroke | stroke-opacity ]#


Exposing fill and stroke to an SVG image

In this example we have a simple SVG embedded using an <img> element.

You first need to specify on the embedding element the properties whose values you wish to expose to the embedded SVG, using the -moz-context-properties property. For example:

.img1 {
  width: 100px;
  height: 100px;
  -moz-context-properties: fill, stroke;
  fill: lime;
  stroke: purple;

Now that you've done this, the SVG image can use the values of the fill and stroke properties, for example:

<img class="img1" src="data:image/svg+xml;utf8,<svg xmlns='http://www.w3.org/2000/svg'>
                       <rect width='100%' height='100%' stroke-width='30px'
                       fill='context-fill red' stroke='context-stroke' fill-opacity='0.5'/></svg>">

Here we've set the image src to a data URI containing a simple SVG image; the <rect> inside has been made to take its fill and stroke values from the fill and stroke set on the <img> element by giving them the context-fill/context-stroke keywords in their values, along with a fallback color for the fill (red) which will be used in the case that the SVG is loaded standalone in a top-level window (where it will have no context element to provide context values). Note that if a color is set directly on the SVG, but then the context color is also specified, the context color overrides the direct color.

Note: You can find a working example on Github.


Not part of any standard.

Browser compatibility

BCD tables only load in the browser

See also