Web/CSS/offset-anchor

The offset-anchor CSS property specifies the point inside the box of an element travelling along an offset-path that is actually moving along the path.

Syntax

/* Keyword values */
offset-anchor: top;
offset-anchor: bottom;
offset-anchor: left;
offset-anchor: right;
offset-anchor: center;
offset-anchor: auto;

/* <percentage> values */
offset-anchor: 25% 75%;

/* <length> values */
offset-anchor: 0 0;
offset-anchor: 1cm 2cm;
offset-anchor: 10ch 8em;

/* Edge offsets values */
offset-anchor: bottom 10px right 20px;
offset-anchor: right 3em bottom 10px;

/* Global values */
offset-anchor: inherit;
offset-anchor: initial;
offset-anchor: unset;

Values

auto: offset-anchor is given the same value as the element's transform-origin, unless offset-path is none, in which case it takes its value from offset-position.
<position>: A <position> defines an x/y coordinate, to place an item relative to the edges of an element's box. It can be defined using one to four values. For more specifics, see the <position> and background-position reference pages. Note that the 3-value position syntax does not work for any usage of <position>, except for in background(-position).

Formal definition

Initial value	`auto`
Applies to	transformable elements
Inherited	no
Percentages	relativeToWidthAndHeight
Computed value	for `<length>` the absolute value, otherwise a percentage
Animation type	a position

Formal syntax

auto | <position>where <position> = [ [ left | center | right ] || [ top | center | bottom ] | [ left | center | right | <length-percentage> ] [ top | center | bottom | <length-percentage> ]? | [ [ left | right ] <length-percentage> ] && [ [ top | bottom ] <length-percentage> ] ]where <length-percentage> = <length> | <percentage>

Examples

Setting various offset-anchor values

In the following example, we have three <div> elements nested in <section> elements. Each <div> is given the same offset-path (a horizontal line 200 pixels long) and animated to move along it. The three are then given different background-color and offset-anchor values.

Each <section> has been styled with a linear gradient to give it a horizontal line running through its center, to give you a visual display of where the <div>'s offset paths are running.

This allows you to see what effect the different offset-anchor values have — the first one, auto, causes the <div>'s center point to move along the path. The other two cause the <div>'s top-right and bottom-left points to move along the path, respectively.

HTML

<section>
  <div class="offset-anchor1"></div>
</section>
<section>
  <div class="offset-anchor2"></div>
</section>
<section>
  <div class="offset-anchor3"></div>
</section>

CSS

div {
  offset-path: path('M 0,20 L 200,20');
  animation: move 3000ms infinite alternate ease-in-out;
  width: 40px;
  height: 40px;
}

section {
  background-image: linear-gradient(to bottom, transparent, transparent 49%, #000 50%, #000 51%, transparent 52%);
  border: 1px solid #ccc;
  margin-bottom: 10px;
}

.offset-anchor1 {
  offset-anchor: auto;   
  background: cyan;
}

.offset-anchor2 {
  offset-anchor: right top;
  background: purple;
}

.offset-anchor3 {
  offset-anchor: left bottom;
  background: magenta;
}

@keyframes move {
  0% {
    offset-distance: 0%;
  }
  100% {
    offset-distance: 100%;
  }
}

Result

Specifications

Specification	Status	Comment
Motion Path Module Level 1The definition of 'offset-anchor' in that specification.	Working Draft	Initial definition

Browser compatibility

Update compatibility data on GitHub

	Desktop						Mobile
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet
`offset-anchor`	Chrome Full support 79	Edge Full support 79	Firefox Full support 72 Full support 72 No support 70 — 72 Disabled' Disabled' From version 70 until version 72 (exclusive): this feature is behind the `layout.css.motion-path.enabled` preference (needs to be set to `true`). To change preferences in Firefox, visit about:config.	IE No support No	Opera No support No	Safari No support No	WebView Android Full support 79	Chrome Android Full support 79	Firefox Android No support No	Opera Android No support No	Safari iOS No support No	Samsung Internet Android Full support 12.0

Legend

Full support: Full support
No support: No support
User must explicitly enable this feature.': User must explicitly enable this feature.