Align Button to the bottom

by Hugo Carneiro

HTML

<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css">
<div class="container">

  <div class="hidden-xs">
    
    <!-- PRICE SQUARES HERE -->
    <div class="parent-container">
      <div class="col-sm-4 column-holder">
        <h3>Free</h3>
				<span><span>$</span>0</span>
				<span>For teams wanting to try out Slack for an unlimited period of time</span>
        
        <a class="btn btn-lg btn-primary" href="#">Get Started Now</a>
      </div>
      <div class="col-sm-4 column-holder">
        <h3>Standard</h3>
				<span><span>$</span>6<span>67</span></span>
				<span>per active user, per month<br>billed annually</span>
				<span>$8 billed monthly</span>
        
        <a class="btn btn-lg btn-primary" href="#">Get Started Now</a>
      </div>
      <div class="col-sm-4 column-holder">
        <h3>Plus</h3>
				<span><span>$</span>12<span>50</span></span>
				<span>per active user, per month<br>billed annually</span>
				<span>$15 billed monthly</span>
        
        <a class="btn btn-lg btn-primary" href="#">Get Started Now</a>
      </div>
    </div>
    
    <!-- DESCRIPTIONS GO HERE -->
    <div class="parent-container">
      <div class="col-sm-4 column-holder-2">
        
        <div>
					<h3>Free includes</h3>
					<p>All of these great features:</p>
				</div>
				<ul>
					<li><span>Searchable message archives, up to 10k of your team’s most recent messages</span></li>
					<li><span>10 apps or service integrations</span></li>
					<li><span>Native apps for iOS, Android, Mac &amp; Windows Desktop</span></li>
					<li><span>Two-person calls</span></li>
					<li><span>5GB total file storage for the team </span></li>
				</ul>
				<div>
					<a>Learn more</a>
					<div>Your current plan</div>
				</div>
        
      </div>
      <div class="col-sm-4 column-holder-2">
        
        <div>
					<h3>Standard includes</h3>
					<p>Everything in <strong>Free</strong>,...

CSS

img {
  max-width: 100%;
  height: auto;
}

.parent-container {
  display: flex;
  justify-content: flex-start;
  flex-flow: wrap;
}

.column-holder,
.column-holder-2 {
  position: relative;
  padding-bottom: 66px;
  text-align: center;
}

.column-holder-2 {
  text-align: left;
}

.column-holder .btn {
  display: block;
  position: absolute;
  bottom: 10px;
  left: 15px;
  right: 15px;
}