I'm making a Bootstrap-based website, in which I have a portfolio zone, in which thumbnails open a respective collapsible DIV. I need when a collapsible DIV is open, the respective thumbnail changes its CSS formatting, in this case color. I tried to add a class to this ".cliente_activo" call through my Javascript, but since I am not an expert in this last language, I did not succeed. I would appreciate if you could help me.
My prototype: