JSFiddle - React, Tailwind, and code Playground

HTML

<body>

  <div class="container">

    <div class="header">
     Header123
    </div>

    <div class="nav">

      <ul>
        <li>HOME</li>
        <li>PROJECT</li>

      </ul>

    </div>

    <div class="main">
      Article
    </div>

    <div class="footer">Footer</div>
  </div>

</body>

CSS

<style type="text/css">

body,html {
  margin: 0;
  padding: 0px;
  text-align: center;
  background-color: blue;
} 

.container
{
  margin: 0;
  background-color: red;
}

.header
{
  text-align: left;
  height: 90px;
  background-color: green;
  margin: 0;
}

.nav
{
  float: right;
  }

.nav ul
{
  list-style: none;
  height: 30px;
  padding: 0px;
  margin: 0px;
}

.nav ul li
{
  margin: 10px;
}


.footer
{

  height:40px;
}

</style>