Live editor to show the page it was launched from

I added a toolbar menu item for the plugin’s Live editor that links to

admin_url( 'admin.php?page=instantcss-customizer' )

When I am on an inner page in the front end, say /sample-page, clicking on the toolbar menu item launches the editor at the left alright but switches to homepage in the right side.

Is there a way to make it dynamic? i.e., remain on the page it was launched from.