Triggering CSS on open and close

I may be asking something obvious, but how would I be able to trigger different CSS depending on whether the open or closed state is clicked on for the individual expands. For example, I need to hide certain div’s on the parent page when the expand element is opened, then restore them when the element is closed back up. Anyone know the best practice for doing this? I have the latest Pro version of the plugin & am also using Collapse Commander (awesome plugins!).

Thanks for you help in advance.

https://wordpress.org/plugins/jquery-collapse-o-matic/