View source for Accordion with heading-button variants

<html>
<body>

<h2>Accordion variants related to headings enclosing expandable buttons</h2>

<div>

<h3>
<button aria-expanded="false">Native h3 heading element encloses native button element here</button>
</h3>
<br>

<div role="heading" aria-level="3">
<button aria-expanded="false">ARIA heading and level encloses native button here</button>
</div>
<br>

<h3 role="heading" aria-level="3">
<button aria-expanded="false">Native heading element with fully-redundant ARIA heading and level here</button>
</h3>
<br>

<h3 aria-level="3">
<button aria-expanded="false">Native heading element with redundant ARIA level but not role here</button>
</h3>
<br>

The following button stands alone, not within a heading at all: 
<br>
<button aria-expanded="false">Hello World</button>
<br>

<h3>This is a plain-text heading as a control case</h3>
that's it!

</div>

</body>
</html>