Here is your revised project file with the js script but it seems the script activates ALL dropdowns with the effect.

Mayby someone who has mad js skills (ERIC) can figure out a fix.......

I still think you could use the Custom Dynamic class to do the same.....but run out of time......mayby when I get some more I can look further at it as the Custom Dynamic class sets the elements property's in a activated state when the class is added usually by jscript.

Here is a working version using script.

This is the link of example I Modified to make work. (as some say Hacked )

https://codepen.io/anephew/pen/VpWRRX