<!doctype html>
<title>CSS Container Queries Test: Canvas as size container for focusable child</title>
<link rel="help" href="https://drafts.csswg.org/css-contain-3/#size-container">
<link rel="match" href="/css/reference/ref-filled-green-100px-square-only.html">
<style>
  @supports (container-type: size) {
    canvas:focus-within {
      border: 50px solid green;
    }
    canvas {
      display: block;
      width: 100px;
      height: 100px;
      box-sizing: border-box;
      container-type: size;
    }
  }
</style>
<p>Test passes if there is a filled green square.</p>
<canvas>
  <div id="target" tabIndex="1"></div>
</canvas>
<script>
  requestAnimationFrame(()=> {
    requestAnimationFrame(()=> {
      target.focus();
    });
  });
</script>
