How to make such a grid?

Question

css

https://jsfiddle.net/5n4jnwnp/1/
The problem is that if I remove the padding from 3 elements, then it becomes disproportionate for others.
Those. There should be 3 (identical) fluid columns with a fixed padding of 15px between them.

Answer 1

jsfiddle.net/yurzui/vq8fexny