html, body {
  height: 100%;
  margin: 0;
}

body {
  display: flex;
  flex-direction: column;
}

.content {
  flex: 1; /* This makes the content area grow and push the footer down */
  padding: 20px;
}

.header, .footer {
  background-color: #333;
  color: white;
  padding: 15px 20px;
  text-align: center;
}