JSFiddle - React, Tailwind, and code Playground

HTML

<div class="wrap">
  <nav class="menu">
    <ul>
      <li>Something</li>
    </ul>
  </nav>
  <div class="container"></div>
</div>

CSS

.wrap {
  width: 100%;
  margin: 0;
  padding: 0;
}

.menu {
  top: 0;
  position: fixed;
  background-color: green;
  width: 100%;
}

.container {
  background-image: url(http://www.spektyr.com/PrintImages/Cerulean%20Cross%203%20Large.jpg);
	background-repeat: no-repeat;
	background-size: 100% 100%;
	background-position: center;
  height: 700px;
}