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).

offset-anchor = 
  auto        |
  <position>  

<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> ]  

<length-percentage> = 
  <length>      |
  <percentage>  

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

• offset
• offset-distance
• offset-rotate
• SVG <path>