t>
<script src="/resources/testdriver-actions.js"></script>
<script src='../../resources/shadow-dom.js'></script>
<script src="../../resources/focus-utils.js"></script>

<style>
.wrapper {
  display: grid;
  reading-flow: grid-order;
}
</style>

<span id="host1" class="test-case" data-expect="b1,a1,c1"
      data-description="Slot assigned element is a grid with reading-flow.">
  <template shadowrootmode="open">
    <style>
    .wrapper {
      display: grid;
      reading-flow: grid-order;
    }
    </styl