Adding a close button to Collapse Sections 2.0

I purchased a collapse plugin, but I'm wondering how to add an 'X' in the reveal section in the upper right corner (the part that opens). This seems like a prominent UI element needed with this type of functionality, but it's not part of it for whatever reason. Also, if I wanted to use the ESC button to close the reveal, how would I do that?

I added a PNG of the X to be used if necessary.

Plugin:

Expand - Collapse Sections 2.0

https://www.sqsmods.com/store/p/expand-collapse-sections-20

Site:

https://toucan-tetra-fwm2.squarespace.com/culture

p: argus