CSS Animatable offset-anchor Property Example

<!DOCTYPE html>
<html>
<head>
<style>
#container {
    width: 330px;
    height: 180px;
    margin: auto;
    position: relative;
    box-shadow: 0 0 10px 0 #aaa;
    background: #333;
}

#circle {
    border: solid red 10px;
    height: 10px;
    width: 10px;
    border-radius: 50%;
    position: absolute;
    z-index: 2;
    box-sizing: border-box;
    offset-path: path('M 30 80 L 300 80');
    animation: circle-anim 5s infinite;
}

#block {
    position: absolute;
    width: 50px;
    height: 50px;
    background: blue;
    z-index: 1;
    offset-path: path('M 30 80 L 300 80');
    offset-anchor: bottom left;
    animation: anchor-anim 5s infinite;
    overflow: visible;
}

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

@keyframes anchor-anim {
    0%    {
      offset-distance: 0%;
      offset-anchor: bottom left;
    }
    50%  { 
      offset-distance: 100%; 
      offset-anchor: top left;
    }
    100%    {
      offset-distance: 0%;
      offset-anchor: bottom left;
    }
}
@keyframes circle-anim {
    0%  { offset-distance: 0%; }
    50%  { offset-distance: 100%; }
    100%  { offset-distance: 0%; }
}
</style>
</head>
<body>

<h1>Animatable 'offset-anchor'  Property</h1>
<hr>

<p>The blue 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 blue box.</p>
  
<div id="container">
	<div id="block"></div>
	<div id="circle"></div>
	<svg>
    	<path d="M 30 80 L 300 80" fill="none" stroke="white" stroke-width="2" stroke-dasharray="5,5"/>
  	</svg>
</div>

</body>
</html>