When this element is clicked, a currently open popup is closed.
Does nothing if no popup is currently open.
Clickin on this
<span> will close a currently open popup:
<span class='up-close'>Close this popup</span>
When a popup changes the current URL, you might need to deal with content being displayed as either a popup or a full page.
To make a link that closes the current popup, but follows to a fallback destination if no popup is open:
<a href="/fallback" up-close>Okay</a>