Dropdown list for setting menu

I'm working on the dropdown list for setting menu.
When a user clicks setting button, it will be shown as dropdown list, not modal window.


So, I googled it to figure it out how to work at React and examples.
Well, I found lots of examples and most of them are provided as a package like react-menu, react-dd-menu, rc-menu, and others.
I downloaded it to check how it works.
But everything that I set up on my test server, they gave me an error.
So I couldn't do with that.

My times were totally waste of times.

Somehow, I did implement that the dropdown is shown when I click the button.
But, this dropdown is shown at the bottom of the window.
So, I'm studying animation on React(https://facebook.github.io/react/docs/animation.html)
and figuring css out with this example (http://codepen.io/anon/pen/jALAjk).