JSFiddle - React, Tailwind, and code Playground

HTML

<form name="useradd" class="form-horizontal text-center" role="form" method="post">
        <div class="modal show" id="useradd_modal">
          <div class="modal-dialog modal-lg">
            <div class="modal-content">
                  <div class="modal-header">
                      <button type="button" class="close" data-dismiss="modal"><span aria-hidden="true">&times;</span><span class="sr-only">Close</span></button>
                      <h4 class="modal-title text-center text-danger">Adding a user</h4>
                  </div><!-- /.modal-header -->
                  <div class="modal-body">
                      <div class="form-group">
                          <div class="col-md-12 center-block text-center">
                          <label class="control-label">Login-Name:</label>
                            <input class="form-control text-center" type="text" placeholder="Login-Name" value="" name="ua_loginname" required="required" />
                          </div>
                      </div>
                      <div class="form-group">
                          <div class="col-md-12 center-block text-center">
                          <label class="control-label">Firstname:</label>
                            <input class="form-control"  type="text" placeholder="Firstname" value="" name="ua_fname" required="required"/>
                          </div>
                      </div>
                  </div><!-- /.modal-body -->
                  <div class="modal-footer">
                    <input class="btn btn-md btn-danger pull-left" data-dismiss="modal" type="submit" value="User add"/>
                    <button type="button" class="btn btn-default" data-dismiss="modal">Close</button>
                  </div><!-- /.modal-footer -->
            </div><!-- /.modal-content -->
          </div><!-- /.modal-dialog -->
        </div><!-- /.modal -->
    </form>

CSS

/*!
 * Bootstrap v3.3.1 (http://getbootstrap.com)
 * Copyright 2011-2014 Twitter, Inc.
 * Licensed under MIT (https://github.com/twbs/bootstrap/blob/master/LICENSE)
 *//*! normalize.css v3.0.2 | MIT License | git.io/normalize */html{font-family:sans-serif;-webkit-text-size-adjust:100%;-ms-text-size-adjust:100%}body{margin:0}article,aside,details,figcaption,figure,footer,header,hgroup,main,menu,nav,section,summary{display:block}audio,canvas,progress,video{display:inline-block;vertical-align:baseline}audio:not([controls]){display:none;height:0}[hidden],template{display:none}a{background-color:transparent}a:active,a:hover{outline:0}abbr[title]{border-bottom:1px dotted}b,strong{font-weight:700}dfn{font-style:italic}h1{margin:.67em 0;font-size:2em}mark{color:#000;background:#ff0}small{font-size:80%}sub,sup{position:relative;font-size:75%;line-height:0;vertical-align:baseline}sup{top:-.5em}sub{bottom:-.25em}img{border:0}svg:not(:root){overflow:hidden}figure{margin:1em 40px}hr{height:0;-webkit-box-sizing:content-box;-moz-box-sizing:content-box;box-sizing:content-box}pre{overflow:auto}code,kbd,pre,samp{font-family:monospace,monospace;font-size:1em}button,input,optgroup,select,textarea{margin:0;font:inherit;color:inherit}button{overflow:visible}button,select{text-transform:none}button,html input[type=button],input[type=reset],input[type=submit]{-webkit-appearance:button;cursor:pointer}button[disabled],html...