I have a simple flex-box layout with a container like:
.grid { display: flex; flex-flow: row wrap; justify-content: space-between; }
Add a ::after which autofills the space. No need to pollute your HTML. Here is a codepen showing it: http://codepen.io/DanAndreasson/pen/ZQXLXj
.grid { display: flex; flex-flow: row wrap; justify-content: space-between; } .grid::after { content: ""; flex: auto; }