LeptonX uses
                    Bootstrap Close Button's 
                    component's latest version. 
                    A generic close button for dismissing content like modals and alerts.
                  
                      Provide an option to dismiss or close a component with .btn-close. Default styling is
                      limited, but highly customizable. Modify the Sass variables to replace the default
                      background-image. Be sure to include text for screen readers, as
                      we’ve done with aria-label.
                    
<button type="button" class="btn-close" aria-label="Close"></button>
 
                      Disabled close buttons change their opacity. We’ve also applied
                      pointer-events: none and user-select: none to preventing hover and
                      active states from triggering.
                    
<button type="button" class="btn-close" disabled aria-label="Close"></button>
 
                      Change the default .btn-close to be white with the
                      .btn-close-white class. This class uses the filter property to invert
                      the background-image.
                    
<div class="bg-dark p-3 rounded">
  <button
    type="button"
    class="btn-close btn-close-white"
    aria-label="Close"
  ></button>
  <button
    type="button"
    class="btn-close btn-close-white"
    disabled
    aria-label="Close"
  ></button>
</div>