JSFiddle - React, Tailwind, and code Playground

HTML

<script src="http://ajax.googleapis.com/ajax/libs/jqueryui/1.8.11/jquery-ui.min.js"></script>
<div class="form"></div>
<div class="box"></div>
<button id="showFormBtn">Show form</button>

CSS

.form {
    width: 30%;
    height: 40%;
    background: white;
    position: absolute;
    z-index: 20;
}

.box {
    position: absolute;
    width: 50%;
    height: 300px;
    line-height: 300px;
    font-size: 50px;
    text-align: center;
    border: 2px solid black;
    left: 150%;
    display:none;
    top: 100px;
    margin-left: -25%;
}
body {
    height: 100%;
}
.background {
    height: 100%;
    width: 100%;
    position: absolute;
    top: 0px;
    left: 0px;
    background: black;
    opacity: 0;
    z-index: 10;
}

JavaScript

var form = $('.form');
var form2 = $('.box');

function positionForm() {
    form.css({
        top: -form.height(),
        left: ($(document.body).width() - form.width()) / 2
    });
}

function addListeners(background) {
    background.click(function() {
        background.fadeOut(300, function() {
            background.remove();
        });
        form.animate({
            top: -form.height() - 10
        }, 300);
        form2.animate({
            left: '100%'
        }, 300);
        setTimeout(function() {
            form2.css('display', 'none');
        }, 301);
    });
}

function showForm() {
    var form = $('.form');
    var form2 = $('.box');
    positionForm();
    form2.css('display', 'block');
    form.animate({
        top: 10
    }, 1500, 'easeOutElastic');
    form2.animate({
        left: '50%'
    }, 1500, 'easeOutElastic');
}

function fadeBackground(callback) {
    var background = $('<div class="background"></div>');
    $(document.body).append(background);
    background.fadeTo(300, 0.5, function() {
        if (typeof callback === 'function') {
            callback();
        }
    });
    addListeners(background);
}

$('#showFormBtn').click(function() {
    fadeBackground(showForm);
});

form.click(function(e) {
    e.stopImmediatePropagation();
});

positionForm();