JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://code.jquery.com/jquery-3.2.1.min.js"></script>
<div class="modalBlock">
    <div class="modalClose">x</div>
    <div class="modalBody">...</div>
</div>

CSS

.modalBlock {
  width: 200px;
  height: 100px;
  padding: 10px;
  background: #aaa;
  position: relative;
}
.modalClose {
    cursor: pointer;
    position: absolute;
    right: 10px;
    top: 10px;
}

JavaScript

$(document).ready(function() {
    var modalBlock = $(".modalBlock");
    var modalClose = $(".modalClose");
    modalClose.click(function() {
        $(this).parent().fadeOut();
    });
});