Requesting further help for "Accessibility Troubleshooting"

Jsfiddle link to my code.

https://jsfiddle.net/xc2y6aLk/1/

I was able to achieve most of the accessibility troubleshoots except for the show/hide comment control.

It wants the show/hide buttons to be accessible to the keyboard, and I am lost on how to achieve this.

My research pointed towards using javascript and programming event listeners.