W3Schools Tryit Editor

<!DOCTYPE html>
<html>
<head>
<style>
  #frameDiv {
    width: 430px;
    height: 180px;
    margin: 20px;
    position: relative;
    border: solid black 1px;
    background-color: rgb(205, 242, 205);
  }

#circleDiv {
    border: solid darkred 3px;
    height: 10px;
    width: 10px;
    border-radius: 50%;
    position: absolute;
    z-index: 2;
    box-sizing: border-box;
    offset-path: path('M 50 80 L 350 80');
    animation: moveCirc 5s 3;
  }

#pinkDiv {
    position: absolute;
    width: 70px;
    height: 70px;
    background-color: hotpink;
    opacity: 0.5;
    z-index: 1;
    offset-path: path('M 50 80 L 350 80');
    offset-anchor: bottom left;
    animation: movePink 5s 3;
    overflow: visible;
  }

svg {
    position: absolute;
    height: 100%;
    width: 100%;
    left: 0;
    top: 0;
  }

@keyframes movePink {
    0%    {
      offset-distance: 0%;
      offset-anchor: bottom left;
    }
    100%  { 
      offset-distance: 100%; 
      offset-anchor: top left;
    }
  }
  @keyframes moveCirc {
    100%  { offset-distance: 100%; }
  }
</style>
</head>
<body>

<h1>The offset-anchor property animated</h1>

<p>The pink element is first "anchored" to the path at the bottom left corner point. Within 5 seconds the achored point is moved to the top left corner of the pink box.</p>
<p><mark><strong>Note:</strong> This property currently only works with the Firefox browser.</mark></p>

</body>
</html>