html {
  height: 100%;
}

body {
  display: flex;
  flex-direction: column;
  min-height: 100vh;
}

body > nav {
  flex-shrink: 0;
}

body > header {
  flex-shrink: 0;
}

body > section {
  flex: 1 0 auto;
}

body > footer {
  flex-shrink: 0;
}