demo/src/app/components/+accordion/demos/opened/opened.html
<accordion>
<accordion-group heading="Content 1">
<p>accordion 1</p>
</accordion-group>
<accordion-group heading="Initially expanded"
[isOpen]="isFirstOpen">
This content is straight in the template.
</accordion-group>
<accordion-group heading="Content 2">
<p>accordion 3</p>
</accordion-group>
</accordion>