JSFiddle - React, Tailwind, and code Playground

HTML

<header>header</header>
<main>
sdf<br>sdf<br>sdf<br>sdf<br>sdf<br>sdf<br>end
</main>
<footer>footer</footer>

CSS

html {
  height: 100%;
  background-color: gray;
}
body {
  min-height: 100%;
  width: 300px;
  margin: 0 auto;
  background-color: red;
  position: relative;
}

header {
  background-color: blue;
}

main {
  padding: 15px 15px 115px 15px;
}

footer {
  position: absolute;
  bottom: 0;
  height: 100px;
  width: 100%;
  background: green;
}