content/test/data/accessibility/css/display-contents.html

<!DOCTYPE html>
<style>
.contents {
  display: contents;
}
</style>

<p><button class="contents">Button</button></p>
<p><button class="contents"><mark>Button</mark></button></p>
<p><div class="contents" role="listbox">Listbox</div></p>
<p>
  <div class="contents" aria-describedby="desc"></div>
  <div class="contents" id="desc">Description</div>
</p>
<div class="contents">Generic</div>
<div><div class="contents">Generic (nested)</div></div>
<div role="main" class="contents" style="display:none"><p>Paragraph inside of hidden main that's also display:contents</p></div>
<div role="complementary" style="display:none"><p class="contents">Display:contents paragraph inside of hidden complementary</p></div>