Responsive landing using HTML, CSS and Javascript

I would like to ask the community for some help. I tried to put a control of velocity that the divs of answer open and close on my page. But I didnt have succesfull in any of my tries. I tried to put "transition" code on my CSS, but it didnt work in my classes of answer. If you have any suggestion or a project that made it, I would fell happy to learn it! :)