Edit in JSFiddle

<div class="flex-container">
<div class="item">
  <h2>Sub Title1</h2>
  <p>Lorem ipsum dolor sit amet, consectetur adipiscing elit, </p>
</div>

<div class="item">
  <h2>Sub Title2</h2>
  <p>Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam,  </p>
</div>

<div class="item">
  <h2>Sub Title3</h2>
  <p>Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur.  </p>
</div>


</div>

*{
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}
*::before, *::after{
  box-sizing: border-box;
}
.flex-container{
display: flex;
padding: 15px;
border: 2px solid #333;
flex-wrap: wrap;

}
.item{
  background-color: #2da192;
  padding: 20px;
  margin: 5px;
  color: #fff;
  flex: 1 0 30%;
}