JSFiddle - React, Tailwind, and code Playground

HTML

<body>
  <div id="header">
    <h1>
      Site Header
    </h1>
  </div>
  <!--Drop-Down Nav-bar-->
  <div id="menu-bar">
    <ul>
      <li>
        <a href="#">
          Home
        </a>
      </li>
      <li>
        <a href="#">
          1
        </a>
        <ul>
          <li>
            <a href="#">
              1-1
            </a>
          </li>
          <li>
            <a href="#">
              1-2
            </a>
          </li>
        </ul>
      </li>
      <li>
        <a href="#">
          2
        </a>
        <ul>
          <li>
            <a href="#">
              2-1
            </a>
          </li>
        </ul>
      </li>
      <li>
        <a href="#">
          3
        </a>
        <ul>
          <li>
            <a href="#" target="_blank">
              3-1
            </a>
          </li>
          <li>
            <a href="#" target="_blank">
              3-2
            </a>
          </li>
          <li>
            <a href="#" target="_blank">
              3-3
            </a>
            <ul>
              <li>
                <a href="#" target="_blank">
                  3-3-1
                </a>
              </li>
              <li>
                <a href="#" target="_blank">
                  3-3-2
                </a>
              </li>
              <li>
                <a href="#" target="_blank">
                  3-3-3
                </a>
              </li>
              <li>
                <a href="#" target="_blank">
                  3-3-4
                </a>
              </li>
            </ul>
          </li>
        </ul>
      </li>
      <li>
        <a href="#">
          4
        </a>
        <ul>
          <li>
            <a href="#" target="_blank">
              4-1
            </a>
          </li>
          <li>
            <a href="#" target="_blank">
              4-2
            </a>
          </li>
          <li>
            <a href="#" target="_blank">
              4-3
   ...

CSS

html {
  height: 100%;
  min-height: 100%;
}
body {
  margin: 0px;
}
#header {
  position: fixed;
  width: 100%;
  margin: 0px;
  background: rgba(67, 69, 76, 0.87);
  padding: 30px;
  text-shadow: 5px 5px 5px #000000;
  text-align: center;
  color: white;
}
#header h1 {
   
  position: center;
  padding: 0px;
  margin: 0px;
}
#menu-bar {
  z-index: 1;
  position: fixed;
  top: 97px;
  width: 100%;
}
#menu-bar ul {
  width: 100%;
  background: rgba(30, 51, 74, 0.74);
  list-style: none;
  position: relative;
  float: left;
  margin: 0;
  padding: 0;
}
#menu-bar ul a {
  display: block;
  color: white;
  text-decoration: none;
  font-weight: 700;
  font-size: 12px;
  line-height: 40px;
  padding: 0 15px;
  font-family: "HelveticaNeue", "Helvetica Neue", Helvetica, Arial, sans-serif;
}
#menu-bar ul li {
  position: relative;
  float: left;
  margin: 0;
  padding: 0;
}
#menu-bar ul li:hover {
  background: rgb(90, 42, 0);
}
#menu-bar ul ul {
 z-index: 2;
  display: none;
  position: absolute;
  top: 100%;
  left: 0;
  background: rgb(32, 42, 60);
}
#menu-bar ul ul li {
  float: none;
}
#menu-bar ul ul a {
  line-height: 120%;
  padding: 10px;
}
#menu-bar ul ul ul {
  top: 0;
  left: 100%
}
#menu-bar ul li:hover > ul {
  display: block;
  background: rgb(32, 42, 60);
}
#section {
  background-color: grey;
  color: black;
  width: 50%;
  height: 66%;
  float: right;
  padding: 50px;
  overflow: hidden;
  position: fixed;
  top: 160px;
  right: 30%;
}
#scroll {
  overflow-y: hidden;
  height: 100%;
    margin-bottom: 15px;
}
#footer {
  position: fixed;
  z-index: 100;
  bottom: 0;
  left: 0;
  width: 100%;
  background: rgb(25, 25, 62);
  background: rgba(25, 25, 62, 0.6);
  color: white;
  text-align: center;
  padding: 5px;
}
strong {
  color: #FF3399;
}