JSFiddle - React, Tailwind, and code Playground

HTML

<div id="DataPane">
    <div id="VisibleContainer">
        <div class="handle">
            
        </div>
    </div>
    <div id="InvisibleContainer">
        <div class="handle">
        </div>
        <div class="dataContainer">
        </div>
    </div>
</div>

CSS

/* DATA PANE */
#DataPane {
  position: absolute;
  width: 100%;
  bottom: 0;
  opacity: 0.5;
  z-index: 20;
}
#DataPane .handle {
  width: 50px;
  margin: 0px auto 0px auto;
  background-color: #333333;
  text-align: center;
  cursor: pointer;
  -webkit-user-select: none;
  box-shadow: 4px 2px 11px rgba(50, 50, 50, 0.75);
}
#DataPane #VisibleContainer .handle {
  height: 20px;
  color: #ffffff;
  border-top-left-radius: 5px;
  border-top-right-radius: 5px;
  border-bottom-right-radius: 0px;
  border-bottom-left-radius: 0px;
}
#DataPane #InvisibleContainer {
  display: none;
}
#DataPane #InvisibleContainer .handle {
  height: 5px;
  box-shadow: 4px 2px 11px rgba(50, 50, 50, 0.75);
}
#DataPane #InvisibleContainer .dataContainer {
  width: 99%;
  height: 49vh;
  margin: 0px auto 0px auto;
  background-color: #333333;
  border-top-left-radius: 5px;
  border-top-right-radius: 5px;
  border-bottom-right-radius: 0px;
  border-bottom-left-radius: 0px;
  box-shadow: 4px 2px 11px rgba(50, 50, 50, 0.75);
}
#DataPane #InvisibleContainer .dataContainer #DataContainer {
  position: absolute;
  background-color: #ffffff;
}

JavaScript

var dataPaneMinimumOpacity;

$(document).ready(function () {
    // Initialise variables
    dataPaneMinimumOpacity = $("#DataPane").css('opacity');
    
    // Data pane
    $("#DataPane .handle").click(function () {
        var duration = 600;

        var invisibleContainer = $("#DataPane #InvisibleContainer");
        if ($(invisibleContainer).is(':visible')) {
            // In this case slideup() actually hides the container
            $(invisibleContainer).slideUp(duration, function () {
                $('#DataPane').fadeTo(duration / 2, dataPaneMinimumOpacity);
            });
        } else {
            $(invisibleContainer).slideDown(duration, function () {
                $('#DataPane').fadeTo(duration / 2, 1);
            });
        }
    })
});