3 column layout, using output from Bourbon Neat.

layout.css

html {
  box-sizing: border-box; }
  
.grid-layout::after {
  clear: both;
  content: "";
  display: table; }
  
  .grid-item {
  margin-bottom: 2em;
  float: left;
  display: block;
  margin-right: 2.35765%;
  width: 31.76157%; }
  .grid-item:last-child {
    margin-right: 0; }
  .grid-item:nth-child(3n) {
    margin-right: 0; }
  .grid-item:nth-child(3n+1) {
    clear: left; }

layout.php

<div class="grid-layout">
    <div class="grid-item">
    </div>
    <div class="grid-item">
    </div>
    <div class="grid-item">
    </div>
    <div class="grid-item">
    </div>
    <div class="grid-item">
    </div>
    <div class="grid-item">
    </div>
</div>