by default open collapse in html code example
Example 1: collapse open by default
class="collapse show"
Example 2: html collapsible open by default
<div data-role="collapsible" data-theme="a" data-content-theme="a">
<h3>Header swatch A</h3>
<p>I'm the collapsible content with a themed content block set to "A".</p>
</div>