Demo modal styles for micromodal.js and corresponding expected html

micromodal.css

/**************************\
  Basic Modal Styles
\**************************/

.modal {
  font-family: -apple-system,BlinkMacSystemFont,avenir next,avenir,helvetica neue,helvetica,ubuntu,roboto,noto,segoe ui,arial,sans-serif;
}

.modal__overlay {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: rgba(0,0,0,0.6);
  display: flex;
  justify-content: center;
  align-items: center;
}

.modal__container {
  background-color: #fff;
  padding: 30px;
  max-width: 500px;
  max-height: 100vh;
  border-radius: 4px;
  overflow-y: auto;
  box-sizing: border-box;
}

.modal__header {
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.modal__title {
  margin-top: 0;
  margin-bottom: 0;
  font-weight: 600;
  font-size: 1.25rem;
  line-height: 1.25;
  color: #00449e;
  box-sizing: border-box;
}

.modal__close {
  background: transparent;
  border: 0;
}

.modal__header .modal__close:before { content: "\2715"; }

.modal__content {
  margin-top: 2rem;
  margin-bottom: 2rem;
  line-height: 1.5;
  color: rgba(0,0,0,.8);
}

.modal__btn {
  font-size: .875rem;
  padding-left: 1rem;
  padding-right: 1rem;
  padding-top: .5rem;
  padding-bottom: .5rem;
  background-color: #e6e6e6;
  color: rgba(0,0,0,.8);
  border-radius: .25rem;
  border-style: none;
  border-width: 0;
  cursor: pointer;
  -webkit-appearance: button;
  text-transform: none;
  overflow: visible;
  line-height: 1.15;
  margin: 0;
  will-change: transform;
  -moz-osx-font-smoothing: grayscale;
  -webkit-backface-visibility: hidden;
  backface-visibility: hidden;
  -webkit-transform: translateZ(0);
  transform: translateZ(0);
  transition: -webkit-transform .25s ease-out;
  transition: transform .25s ease-out;
  transition: transform .25s ease-out,-webkit-transform .25s ease-out;
}

.modal__btn:focus, .modal__btn:hover {
  -webkit-transform: scale(1.05);
  transform: scale(1.05);
}

.modal__btn-primary {
  background-color: #00449e;
  color: #fff;
}



/**************************\
  Demo Animation Style
\**************************/
@keyframes mm-fadeIn {
    from { opacity: 0; }
      to { opacity: 1; }
}

@keyframes mm-slideIn {
  from { transform: translateY(35%); }
    to { transform: translateY(0); }
}

.micromodal-slide[aria-hidden="false"] .modal__overlay {
  animation: mm-fadeIn .3s cubic-bezier(0.0, 0.0, 0.2, 1);
}

.micromodal-slide[aria-hidden="false"] .modal__container {
  animation: mm-slideIn .3s cubic-bezier(0, 0, .2, 1);
}

.micromodal-slide .modal__container,
.micromodal-slide .modal__overlay {
  will-change: transform;
}

micromodal.html

  <div class="modal micromodal-slide" id="modal-1" aria-hidden="true">
    <div class="modal__overlay" tabindex="-1" data-micromodal-close>
      <div class="modal__container" role="dialog" aria-modal="true" aria-labelledby="modal-1-title" aria-describedby="modal-1-content">
        <div role="document">
          <header class="modal__header">
            <h3 class="modal__title" id="modal-1-title">
              Micromodal
            </h3>
            <button class="modal__close" aria-label="Close modal" aria-controls="modal__container1" data-micromodal-close></button>
          </header>
          <main class="modal__content" id="modal-1-content">
            <p>
              Try hitting the <code>tab</code> key and notice how the focus stays within the modal itself. Also, <code>esc</code> to close modal.
            </p>
          </main>
          <footer class="modal__footer">
            <button class="modal__btn modal__btn-primary">Continue</button>
            <button class="modal__btn" data-micromodal-close aria-label="Close this dialog window">Close</button>
          </footer>
        </div>
      </div>
    </div>
  </div>