<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>
<li><a href = "#" id ="sign" data-toggle="modal" data-target="#login-modal"> Login/Register</a> </li>
<div class="modal fade" tabindex="-1" role="dialog" aria-labelledby="gridSystemModalLabel" id= "login-modal">
<div class="modal-dialog" role="document">
<div class="modal-content">
<div class="modal-header">
<button type="button" class="close" data-dismiss="modal" aria-label="Close"><span aria-hidden="true">×</span></button>
<h4 class="modal-title" id="gridSystemModalLabel">Modal title</h4>
</div>
<div class="modal-body">
<h1>Login to Your Account</h1><br>
<form>
<input type="text" name="user" placeholder="Username">
<input type="password" name="pass" placeholder="Password">
<input type="submit" name="login" class="login loginmodal-submit" value="Login">
</form>
</div>
</div>
<div class="modal-footer">
<button type="button" class="btn btn-default" data-dismiss="modal">Close</button>
<button type="button" class="btn btn-primary">Save changes</button>
</div>
</div>
</div>
</div>
