JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://cdnjs.cloudflare.com/ajax/libs/velocity/1.4.1/velocity.min.js"></script>
<section class="cd-section">
  <p>
    Lorem ipsum dolor sit amet, consectetur adipisicing elit. Non ipsum repudiandae sequi ut optio reiciendis consectetur, cum, a provident, iusto quod esse, perferendis iure iste! Quidem itaque, exercitationem aliquam, mollitia recusandae repellat dolores
    quibusdam minima quae reprehenderit ut, reiciendis officia.
  </p>

  <div class="cd-modal-action">
    <a href="#0" class="btn" data-type="modal-trigger">Fire Modal Window</a>
    <span class="cd-modal-bg"></span>
  </div>
  <!-- cd-modal-action -->

  <div class="cd-modal">
    <div class="cd-modal-content">
      <p>
        Lorem ipsum dolor sit amet, consectetur adipisicing elit. Ad modi repellendus, optio eveniet eligendi molestiae? Fugiat, temporibus! A rerum pariatur neque laborum earum, illum voluptatibus eum voluptatem fugiat, porro animi tempora? Sit harum nulla,
        nesciunt molestias, iusto aliquam aperiam est qui possimus reprehenderit ipsam ea aut assumenda inventore iste! Animi quaerat facere repudiandae earum quisquam accusamus tempora, delectus nesciunt, provident quae aliquam, voluptatum beatae quis
        similique in maiores repellat eligendi voluptas veniam optio illum vero! Eius, dignissimos esse eligendi veniam.
      </p>

      <p>
        Lorem ipsum dolor sit amet, consectetur adipisicing elit. Ad modi repellendus, optio eveniet eligendi molestiae? Fugiat, temporibus! A rerum pariatur neque laborum earum, illum voluptatibus eum voluptatem fugiat, porro animi tempora? Sit harum nulla,
        nesciunt molestias, iusto aliquam aperiam est qui possimus reprehenderit ipsam ea aut assumenda inventore iste! Animi quaerat facere repudiandae earum quisquam accusamus tempora, delectus nesciunt, provident quae aliquam, voluptatum beatae quis
        similique in maiores repellat eligendi voluptas veniam optio illum vero! Eius, dignissimos esse eligendi...

CSS

/* -------------------------------- 

Primary style

-------------------------------- */

*,
*::after,
*::before {
  -webkit-box-sizing: border-box;
  -moz-box-sizing: border-box;
  box-sizing: border-box;
}
html {
  font-size: 62.5%;
}
body {
  font-size: 1.6rem;
  font-family: "Source Sans Pro", sans-serif;
  color: #34383c;
  background-color: #ffffff;
}
body.overflow-hidden {
  /* used when modal is visible */
  overflow: hidden;
}
a {
  color: #03bb91;
  text-decoration: none;
}
/* -------------------------------- 

Main Components 

-------------------------------- */

header {
  position: relative;
  height: 160px;
  line-height: 160px;
}
header h1 {
  font-size: 2.4rem;
  text-align: center;
}
@media only screen and (min-width: 1170px) {
  header {
    height: 240px;
    line-height: 240px;
  }
  header h1 {
    font-size: 3.2rem;
    font-weight: 300;
  }
}
.cd-section {
  padding: 2em 5%;
  text-align: center;
  background-color: #03bb91;
}
.cd-section p {
  margin: 2em 0;
  line-height: 1.6;
  color: #ffffff;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}
@media only screen and (min-width: 768px) {
  .cd-section {
    padding: 4em 10%;
  }
  .cd-section p {
    font-size: 1.8rem;
    line-height: 2;
  }
}
@media only screen and (min-width: 1170px) {
  .cd-section {
    padding: 4em 20%;
  }
}
.cd-modal {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  visibility: hidden;
  opacity: 0;
  pointer-events: none;
  -webkit-transition: visibility 0s 0.3s, opacity 0.3s 0s, z-index 0s 0.3s;
  -moz-transition: visibility 0s 0.3s, opacity 0.3s 0s, z-index 0s 0.3s;
  transition: visibility 0s 0.3s, opacity 0.3s 0s, z-index 0s 0.3s;
}
.cd-modal::after {
  /* gradient overlay at bottom of modal window */
  content: '';
  position: absolute;
  left: 0;
  bottom: 0;
  width: 100%;
  height: 60px;
  pointer-events: none;
  background: transparent;
  background: -webkit-linear-gradient(bottom, #34383c, rgba(52,...

JavaScript

jQuery(document).ready(function($) {

  //trigger the animation - open modal window
  $('[data-type="modal-trigger"]').on('click', function() {
  
	var $this = $(this);
  if($this.hasClass('toggle')) {
  	if($this.hasClass("toggle-open")) {
    	closeModal();
    	return false;
    }
  	$this.addClass("toggle-open");
  }

    var actionBtn = $(this),
      scaleValue = retrieveScale(actionBtn.next('.cd-modal-bg'));

    actionBtn.addClass('to-circle');
    actionBtn.next('.cd-modal-bg').addClass('is-visible').one('webkitTransitionEnd otransitionend oTransitionEnd msTransitionEnd transitionend', function() {
      animateLayer(actionBtn.next('.cd-modal-bg'), scaleValue, true);
    });

    //if browser doesn't support transitions...
    if (actionBtn.parents('.no-csstransitions').length > 0) animateLayer(actionBtn.next('.cd-modal-bg'), scaleValue, true);
  });
});

// trigger the animation - close modal window
$('.cd-section .cd-modal-close').on('click', function() {
  closeModal();
});

$(document).keyup(function(event) {
  if (event.which == '27') closeModal();
});

$(window).on('resize', function() {
  //on window resize - update cover layer dimention and position
  if ($('.cd-section.modal-is-visible').length > 0) window.requestAnimationFrame(updateLayer);
});

function retrieveScale(btn) {
  var btnRadius = btn.width() / 2,
    left = btn.offset().left + btnRadius,
    top = btn.offset().top + btnRadius - $(window).scrollTop(),
    scale = scaleValue(top, left, btnRadius, $(window).height(), $(window).width());

  btn.css('position', 'fixed').velocity({
    top: top - btnRadius,
    left: left - btnRadius,
    translateX: 0,
  }, 0);

  return scale;
}

function scaleValue(topValue, leftValue, radiusValue, windowW, windowH) {
  var maxDistHor = (leftValue > windowW / 2) ? leftValue : (windowW - leftValue),
    maxDistVert = (topValue > windowH / 2) ? topValue : (windowH - topValue);
  return Math.ceil(Math.sqrt(Math.pow(maxDistHor, 2) + Math.pow(maxDistVert,...