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">
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.6/js/bootstrap.min.js"></script>
<div class="row">
    <div class="panel panel-user-register">
        <div class="panel-heading">
            <div class="h3" class="panel-title">
                <span class="glyphicon glyphicon-user"></span> Register yourself as operator
            </div>
            <h5>You will soon receive a confirmation e-mail.</h5>
        </div>
        
        <div class="panel-body">
            <div class="row">

                <form class="form-horizontal" id="user-register-form" action="http://local-tb.com/main/user_register" method="post" role="form" style="display: block;">
                    <input type="hidden" name="ci_csrf_token" value="" />
                    
                    <div class="form-group ">
                        <label for="username" class="col-sm-offset-2 col-sm-3 control-label">User Name</label>
                        <div class="col-sm-7 col-sm-offset-right-2">
                            <input type="text" class="form-control" id="username" name="username" placeholder="User Name" maxlength="100">
                        </div>
                    </div>

                    <div class="form-group ">
                        <label for="email" class="col-sm-offset-2 col-sm-3 control-label">Email</label>
                        <div class="col-sm-7 col-sm-offset-right-2">
                            <input type="email" class="form-control" id="email" name="email" placeholder="Email" maxlength="100">
                        </div>
                    </div>

                    <div class="form-group ">
                        <label for="password" class="col-sm-offset-2 col-sm-3 control-label">Password</label>
                        <div...

CSS

body {
    padding: 0px;
    border: 1px solid red;
    background:#E6E6E6;
}

.container{
    border: 1px solid navy;
    padding: 0px;
    background:#E6E6E6;
}
.row{
    margin: 5px;
    background:#E6E6E6;
}

.panel-heading {
    color: #00415d;
    background-color:#E6E6E6;
    border-color:#E6E6E6;
    text-align:center;
}
.panel-body  {
    padding-top: 2px;
    padding-bottom: 20px;
    background:#E6E6E6;
}
.btn-group {
/*    overflow: hidden;  */
    display: block;
    margin-top: 10px;
    margin-bottom: 10px;
    margin-left: 5px;
    margin-right: 5px;
    border: 0px dotted maroon;
}


.col-xs-offset-right-3 {
    margin-right: 25%;
}
.col-xs-offset-right-2 {
    margin-right: 16.66666667%;
}
.col-xs-offset-right-1 {
    margin-right: 8.33333333%;
}
.col-xs-offset-right-0 {
    margin-right: 0;
}