JSFiddle - React, Tailwind, and code Playground

HTML

<body>
  <div class="first">
    <h1>First Box</h1>
  </div>
  <div class="second">
    <h1>Second Box</h1>
  </div>
  <div class="third">
    <h1>Third Box</h1>
  </div>
</body>

CSS

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

div {
    height: 100%;
    text-align: center;
}

.first {
    background: #ccc;
}

.second {
    background: #999
}

.third {
    background: #000
}

h1 {
    color: white;
    padding-top: 100px;
}