<div class="test">
 <div class="btn btn-primary"> I am a button </div>
<button class="btn btn-primary">  I am a button </button>
<a href="#" class="btn btn-primary"> I am a button </a>
</div>
  

.test {
  padding: 1em;
  > * {
    margin-right: .5em
  }
}