JSFiddle - React, Tailwind, and code Playground

HTML

<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="utf-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1">
    
    <meta name="description" content="">
    <meta name="author" content="">
    <link rel="icon" href="../../favicon.ico">

    <title>Center align contents in Span and Section</title>

    <!-- Bootstrap core CSS -->
    <link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.4/css/bootstrap.min.css">

<style>
body {
  padding-top: 50px;
}
.spacer {
    margin-top: 2%;
    margin-bottom: 2%;
}     

.center-this-block {
  position: absolute;
  left: 0;
  right: 0;
  margin: auto;  
}
.borders {
    border-radius: 5px 5px 5px 5px;
    -moz-border-radius: 5px 5px 5px 5px;
    -webkit-border-radius: 5px 5px 5px 5px;
    border: 2px solid #000000;
}     
</style>

</head>

<body>

    <nav class="navbar navbar-inverse navbar-fixed-top ">
      <div class="container">
        <div class="navbar-header">
          <button type="button" class="navbar-toggle collapsed" data-toggle="collapse" data-target="#navbar" aria-expanded="false" aria-controls="navbar">
            <span class="sr-only">Toggle navigation</span>
            <span class="icon-bar"></span>
            <span class="icon-bar"></span>
            <span class="icon-bar"></span>
          </button>
          <a class="navbar-brand " href="#">Project name</a>
        </div>
        <div id="navbar" class="collapse navbar-collapse">
          <ul class="nav navbar-nav navbar-right">
            <li class="active"><a href="#">Home</a></li>
            <li><a href="#about">About</a></li>
            <li><a href="#contact">Contact</a></li>
          </ul>
        </div><!--/.nav-collapse -->
      </div>
    </nav>

<div class="container col-lg-12 spacer"></div>
    

    
<div class="container body-content">
    <ul id="CategoryMenu" class="row list-inline text-center">
        <li>
      ...