JSFiddle - React, Tailwind, and code Playground

HTML

<div class="modal">
  <div class="modal-inner">
   <input type="text" value="Имя">
   <input type="text" value="Телефон">
   <input type="submit" value="Отправить">
  </div>
 </div>
 <button>Заказать звонок</button>

CSS

body {
  text-align: center;
}
.modal {
  position: fixed;
  top: 50%;
  left: 50%;
  z-index: 1;
  display: none;
  margin: 0 auto;
  margin-top: -100px;
  margin-left: -175px;
  width: 350px;
  height: 200px;
  background: #fff;
  border: 3px solid #000;
  border-radius: 3px;
  font-size: 15px;
}
.modal-inner {
  display: table-cell;
  height: 100%;
  vertical-align: middle;
  text-align: center;
  padding-top: 30px;
}
.modal-inner input {
  margin-bottom: 10px;
}
.modal-inner input[type=text] {
  display: inline-block;
  width: 300px;
  height: 30px;
  text-indent: 10px;
}
.modal-inner input[type=submit] {
  display: inline-block;
  margin-top: 10px;
  width: 100px;
  height: 25px;
  cursor: pointer;
}
button {
  margin-top: 50px;
  padding: 0;
  border: 0;
  border-bottom: 1px dashed #000;
  background: 0;
  font-size: 22px;
  cursor: pointer;
}
button:hover {
  border-bottom: 1px dashed transparent;
}
#close {
  position: absolute;
  top: 0;
  right: 0;
  width: 30px;
  height: 30px;
  background: #000;
  color: #fff;
  cursor: pointer;
  text-align: center;
  font-size: 15px;
  line-height: 30px;
}
#bg-close {
  position: fixed;
  top: 0;
  left: 0;
  z-index: 0;
  width: 100%;
  height: 100%;
  background: rgba(0, 0, 0, 0.5);
  cursor: pointer;
}

JavaScript

$(document).ready(function() {
    $('button').click(function() {
      $('.modal')
      .fadeIn(500)
      .css('display', 'table');  
      $('<div id="close">X</div>').appendTo('.modal');
      $('<div id="bg-close"></div>').appendTo('body');
    

    $('#close').click(function() {
      $('.modal')
      .fadeOut(500)
      $('#bg-close').css('display', 'none');
    });

    $('#bg-close').click(function() {
      $(this).css('display', 'none');
      $('.modal')
      .fadeOut(500)
    });    });});