Based on CSS3 dynamic background login box code_html/css_WEB-ITnose

<div class="htmleaf-container">        <div class="wrapper">            <div class="container">                <h1>Welcome</h1>                <form class="form">                    <input type="text" placeholder="Username">                    <input type="password" placeholder="Password">                    <button type="submit" id="login-button">Login</button>                </form>            </div>            <ul class="bg-bubbles">                <li></li>                <li></li>                <li></li>                <li></li>                <li></li>                <li></li>                <li></li>                <li></li>                <li></li>                <li></li>            </ul>        </div>    </div>    <script src="js/jquery-2.1.1.min.js" type="text/javascript"></script>    <script>        $('#login-button').click(function (event) {            event.preventDefault();            $('form').fadeOut(500);            $('.wrapper').addClass('form-success');        });    </script>