Glad i came across this, thanks for posting this.
Just wanted to add to this that the code above can be added to an Elementor Button Module, to get a button to trigger the slideout.
From within the Button Module:
in the link field paste :
<!– slideout toggle –>
in the class field paste:
slideout-toggle
in the custom css paste:
.slideout-toggle a:before {font-family: GeneratePress;}