Buttons - Sizing

Wrap a series of buttons with a .btn-group. 

<div class="btn-group btn-group-lg">
    ...
  </div>
  <div class="btn-group">
    ...
  </div>
  <div class="btn-group btn-group-sm">
    ...
  </div>
  <div class="btn-group btn-group-xs">
    ...
  </div>