How to make div be under all elements with float property?

Question

css

JSFiddle
How to make #description be under all elements? That is, it starts on a new line after all elements. I see it starts on a new line because #data {height: 0}. And why 0, I HZ. I'm not strong in CSS, although I've been quietly studying it for two years now.
The hitch with floats, obviously.

Answer 1

jsfiddle.net/login2030/sbs0w9rh/2
pay attention to .clear{clrear: both;}
I write this class for each of my projects, it kills floats. Very comfortably.

Answer 2

So