JSFiddle - React, Tailwind, and code Playground

HTML

<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.6/css/bootstrap.min.css">
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.6/css/bootstrap-theme.min.css">
<div class="container">
            <div class="row">
                <div class="col-md-6 col-md-offset-3">
                    <div class="panel login-tab">
                        <div class="panel-heading">
                            <div class="row">
                                <div class="col-xs-6">
                                    <a href="#" class="active" id="login-link">Login</a>
                                </div>
                                <div class="col-xs-6">
                                    <a href="#" id="register-link">Register</a>
                                </div>
                            </div>
                            <hr>
                        </div>
                        <div class="panel-body">
                            <div class="row">
                                <div class="col-lg-12">
                                    <form id="login-form" method="post" style="display:block;">
                                        <div class="form-group">
                                            <input type="text" name="username" id="username" tabindex="1" class="form-control" placeholder="Username" value="">
                                        </div>
                                        <div class="form-group">
                                            <input type="password" name="password" id="password" tabindex="2" class="form-control" placeholder="Password">
                                        </div>
                                        <div class="form-group">
                                            <input type="checkbox" tabindex="3" class="" name="remember" id="remember">
                                            <label for="remember">Remember me</label>
                   ...

CSS

html,body {
  height:100%;
  min-height:100%;
  max-height:100%;
}

.container {
    position: fixed;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
}