Gutter doesn't work

[BigAppear]

Hello,

I followed documentation about gutter, with this code:

<div>
  <div class="row xs-gutter no-vert-gutter">
    <div class="col-sm-4" style="border: solid black 1px">
      <p>hello</p>
    </div>
    <div class="col-sm-4" style="border: solid black 1px">
      <p>hi</p>
    </div>
    <div class="col-sm-4" style="border: solid black 1px">
      <p>hey</p>
    </div>
  </div>
</div>

Seems like gutter doesn’t work for me.
Here is before gutter:

And here is after:

When I take off no-vert-gutter, the same happens (but vertically).
Did I miss something ?