apper"></slot>
  </template>
  <button style="order: 2" id="a2">Item A</button>
  <button style="order: 1" id="b2">Item B</button>
  <button style="order: 3" id="c2">Item C</button>
</span>
<br>

<span id="host3" class="test-case" data-expect="o1,o3,o5,host3/o2,host3/o4"
      data-description="Slot is inside a grid container with reading-flow.">
  <template shadowrootmode="open">
    <style>
    .wrapper {
      display: grid;
      reading-flow: grid-order;
    }
    </style>
    <div class="wrapper">
   