JSFiddle - React, Tailwind, and code Playground

HTML

<div id="header">
    <center>
         <h2>OMS Tutoring Database</h2>
    </center>
</div>
<div class="nav-container">
    <ul>
         <li><a class="tutor-button" href="tutoring.php">Tutoring List</a></li>
         <li><a class="add-button" href="addform.php">Add Students</a>
         <li><a class="admin-button" href="admin.php">Admin</a></li>
    </ul>
</div>

CSS

html * {
       font-family: Verdana, Geneva, sans-serif;
   }
   body {
       padding:0px;
       margin:0px;
   }
   .nav-container {
       width:460px;
       margin: 0 auto;
   }
   .nav-container ul {
       padding: 0px;
       list-style:none;
       float:left;
   }
   .nav-container ul li {
       display: inline;
   }
   .nav-container ul a {
       text-decoration:none;
       padding:5px 0;
       width:150px;
       color: #ffffff;
       background: #317b31;
       float:left;
       border-left: 1px solid #fff;
       text-align:center;
   }
   .nav-container ul a:hover {
       background: #92e792;
       color: black;
   }
   #add-form .add-button, #tutor-list .tutor-button, #admin .admin-button {
       color: #ffffff;
       background: #12b812;
   }