<link href="//maxcdn.bootstrapcdn.com/bootstrap/3.3.0/css/bootstrap.min.css" rel="stylesheet" id="bootstrap-css">
<script src="//maxcdn.bootstrapcdn.com/bootstrap/3.3.0/js/bootstrap.min.js"></script>
<script src="//code.jquery.com/jquery-1.11.1.min.js"></script>
<div class="container">
<div class="row">
<a class="btn btn-primary" href="#" data-toggle="modal" data-target=".login-register-form">
Login - Registration Modal
</a>
<div class="modal fade login-register-form" role="dialog">
<div class="modal-dialog modal-sm">
<div class="modal-content">
<div class="modal-header">
<button type="button" class="close" data-dismiss="modal">
<span class="glyphicon glyphicon-remove"></span>
</button>
<ul class="nav nav-tabs">
<li class="active"><a data-toggle="tab" href="#login-form"> Login <span class="glyphicon glyphicon-user"></span></a></li>
<li><a data-toggle="tab" href="#registration-form"> Register <span class="glyphicon glyphicon-pencil"></span></a></li>
</ul>
</div>
<div class="modal-body">
<div class="tab-content">
<div id="login-form" class="tab-pane fade in active">
<form action="/">
<div class="form-group">
<label for="email">Email:</label>
<input type="email" class="form-control" id="email" placeholder="Enter email" name="email">
</div>
<div class="form-group">
<label for="pwd">Password:</label>
<input type="password" class="form-control" id="pwd" placeholder="Enter password" name="pwd">