offset

offset: path("M 20 60 L 120 60 L 70 10 L 20 60") 0% auto 90deg;

offset: path(
    "M 20 210 L 74 210 L 118 140 \
 L 62 140 L 20 210"
  )
  20% auto;

<section class="default-example" id="default-example">
  <div class="wrapper">
    <div id="example-element"></div>
  </div>
  <button id="playback" type="button">再生</button>
</section>

#example-element {
  width: 24px;
  height: 24px;
  background: #2bc4a2;
  clip-path: polygon(0% 0%, 70% 0%, 100% 50%, 70% 100%, 0% 100%, 30% 50%);
  animation: distance 3000ms infinite normal ease-in-out;
  animation-play-state: paused;
}
#example-element.running {
  animation-play-state: running;
}
.wrapper {
  height: 220px;
  width: 200px;
  background:
    url('data:image/svg+xml;utf8,<svg xmlns="https://www.w3.org/2000/svg" viewBox="0 0 150 140" width="200" height="140"><path d="M 0 60 L 100 60 L 50 10 L 0 60" fill="none" stroke="lightgrey" stroke-width="2" stroke-dasharray="4.5"/></svg>')
      no-repeat,
    url('data:image/svg+xml;utf8,<svg xmlns="https://www.w3.org/2000/svg" viewBox="0 -140 150 230" width="200" height="230"><path d="M 0 70 L 56 70 L 98 0 L 42 0 L 0 70" fill="none" stroke="lightgrey" stroke-width="2" stroke-dasharray="4.5"/></svg>');
}
@keyframes distance {
  to {
    offset-distance: 100%;
  }
}
#playback {
  position: absolute;
  top: 0;
  left: 0;
  font-size: 1em;
}

window.addEventListener("load", () => {
  const example = document.getElementById("example-element");
  const button = document.getElementById("playback");
  button.addEventListener("click", () => {
    if (example.classList.contains("running")) {
      example.classList.remove("running");
      button.textContent = "再生";
    } else {
      example.classList.add("running");
      button.textContent = "停止";
    }
  });
});

/* オフセット位置 */
offset: auto;
offset: 10px 30px;
offset: none;
/* オフセット経路 */
offset: ray(45deg closest-side);
offset: path("M 100 100 L 300 100 L 200 300 z");
offset: url(arc.svg);
/* オフセット経路に距離と回転が加わったもの */
offset: url(circle.svg) 100px;
offset: url(circle.svg) 40%;
offset: url(circle.svg) 30deg;
offset: url(circle.svg) 50px 20deg;
/* オフセットアンカーを含む */
offset: ray(45deg closest-side) / 40px 20px;
offset: url(arc.svg) 2cm / 0.5cm 3cm;
offset: url(arc.svg) 30deg / 50px 100px;
/* グローバル値 */
offset: inherit;
offset: initial;
offset: revert;
offset: revert-layer;
offset: unset;

<div id="offsetElement"></div>

@keyframes move {
  from {
    offset-distance: 0%;
  }
  to {
    offset-distance: 100%;
  }
}
#offsetElement {
  width: 50px;
  height: 50px;
  background-color: blue;
  offset: path("M 100 100 L 300 100 L 200 300 z") auto;
  animation: move 3s linear infinite;
}