Last-child doesn't help. How to remove margin from the last block?

Question

css

Codepen.io/anon/pen/NGvEQb Last-child doesn't help .
And if you write directly to the class right

.right {
    margin: 0;
}

then nothing will change until I instead

.col {
     width: calc((100%/3) - 30px);
     margin-right: 30px;
    background: green;
    float: left;
}

I won't prescribe

.col {
     width: calc((100%/3) - 30px);
     margin-right: 45px;
    background: green;
    float: left;  
}

Answer 1

What are you driving?
Maybe that's better?
Well, or if it's really hot, here's your example
!!!!!
and in general it’s time to forget about float, there has long been a property display: flex, which now all browsers are eating if ie8 support is not needed

Answer 2

And I did it:

.col:last-child {
  margin-right: 0;
}