JSFiddle - React, Tailwind, and code Playground

HTML

<!doctype html>
<html lang="en">
  <body>
    <nav>
      <ul>
        <li>
          <a href="#">
            test1
          </a>
        </li>
        <li>
          <a href="#">
            test2
          </a>
        </li>
        <li>
          <a href="#">
            test3
          </a>
        </li>
        <li>
          <a href="#">
            test4
          </a>
        </li>
        <li>
          <a href="#">
            test5
          </a>
        </li>
        <li>
          <a href="#">
            test6
          </a>
        </li>
      </ul>
    </nav>
    <div class="info">
      Test cordinates by clicking<br>
      X = <span data-x>0</span><br>
      Y = <span data-y>0</span><br>
      <b>ABCDEFGHIJKLMNOPQRSTUVWXYZ</b>
    </div>
  </body>
</html>

CSS

* {
  margin: 0;
  box-sizing: border-box;
  transition: all 0.2s;
}

html, body {
  width: 100%;
  height: 100%;
  overflow: hidden;
}

body {
  font-family: arial;
  font-size: 20px;
  line-height: 1.5;
  padding: 100px 40px 0;
  background: #eee;
  position: fixed;
  top: 0;
  left: 0;
}

nav {
  display: block;
  width: 100%;
  position: fixed;
  z-index: 13;
  top: 0;
  left: 0;
  font-size: 15px;
  letter-spacing: 0.1em;
  background: #333;
}

nav ul {
  list-style: none;
  height: 60px;
}

nav ul li {
  float: left;
  height: 60px;
}

nav ul li a {
  display: inline-block;
  height: 60px;
  line-height: 60px;
  padding: 0 25px;
  color: #fff;
  border-left: 1px solid #777;
  text-transform: uppercase;
  text-decoration: none;
}

nav ul li a:hover {
  background: #444;
}

nav ul li:last-child a {
  border-right: 1px solid #777;
}

.info {
  float: left;
  width: 100%;
}

b {
  font-weight: normal;
  letter-spacing: 5px;
}

JavaScript

document.addEventListener('click',function(e) {
  e.preventDefault();
  document.querySelector('[data-x]').innerHTML = e.pageX;
  document.querySelector('[data-y]').innerHTML = e.pageY;
});