Sticky Footer with Flexbox

index.html

<div class="content">
  <h1>Sticky Footer with Flexbox</h1>
  <p><button id="add">Add Content</button></p>
</div>

<footer class="footer">
  Footer 
</footer>

style.css

html {
  height: 100%;
}
body {
  display: flex;
  flex-direction: column;
  height: 100vh; /* Avoid the IE 10-11 `min-height` bug. */
}
.content {
  flex: 1 0 auto; /* Prevent Chrome, Opera, and Safari from letting these items shrink to smaller than their content's default minimum size. */
  padding: 20px;
}
.footer {
  flex-shrink: 0; /* Prevent Chrome, Opera, and Safari from letting these items shrink to smaller than their content's default minimum size. */
  padding: 20px;
}