How to create div with curve in css and html5?

Question

I am newbie in css world and I am trying to make responsive design like this using bootstrap,css and html5.

but ended up like this.

how to create same

Answer 1

You should use percentage to define the border-radius, in this way the curve will look like the one you want.

border-radius: 100%

http://codepen.io/FezVrasta/pen/XKvkJX?editors=1100