JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://bgrins.github.io/spectrum/spectrum.js"></script>
<link rel="stylesheet" href="https://bgrins.github.io/spectrum/spectrum.css">
<h2>Design your own calendar's colors!</h2>
<p>Choose an outside and inside color</p>

<div id="control-container">
  <label for="outside" class="color-label">Outside Color
    <input type="text" name="outside" class="colorpicker">
  </label>
  <label for="inside" class="color-label" id="inside-color-label">Inside Color
    <input type="text" name="inside" class="colorpicker">
  </label>
</div>
<div id="result">&nbsp;</div>

<div id="calendar-position">
 <div class="container" id="outside-preview">
    <div class="container" id="inside-preview">
       <div id="image-square"></div>
    </div>
 </div>
</div>

CSS

#control-container {
  margin: 50px auto;
}
.color-label {
  display: inline-block;
  font-size: 1.3em;
}
#inside-color-label {
  margin-right: 150px;
}
#calendar-position {
  margin: 0 auto;
  width: 500px;
}
#outside-preview, #inside-preview {
  border: 1px solid black;
  border-radius: 8px;
}
#outside-preview {
  width: 500px;
  height: 600px;
  position: relative;
  border-bottom-left-radius: 0px;
  border-bottom-right-radius: 0px;
}
#inside-preview {
   width: 440px;
  height: 568px;
  position: absolute;
  z-index: 1;
  left:5.5%;
  bottom: 0;
  background: #FFF;
 }
 #image-square {
  top: 17px;
  width: 400px;
  height: 176px;
  background: #FFF;
  position: relative;
  display: block;
  z-index: 2;
  margin: 0 auto;
}

JavaScript

$(document).ready(function() {

  $(".colorpicker").spectrum({
    color: "#FFF",
    showInput: true,
    className: "full-spectrum",
    showInitial: true,
    showPalette: true,
    showSelectionPalette: true,
    maxSelectionSize: 10,
    preferredFormat: "hex",
    localStorageKey: "spectrum.demo",
    change: function(color) {
    	var eq =  $(this).index('.colorpicker');
      $('.container').eq(eq).css('background-color', color.toHexString())
    },
    palette: [
      ["rgb(0, 0, 0)", "rgb(67, 67, 67)", "rgb(102, 102, 102)",
        "rgb(204, 204, 204)", "rgb(217, 217, 217)", "rgb(255, 255, 255)"
      ],
      ["rgb(152, 0, 0)", "rgb(255, 0, 0)", "rgb(255, 153, 0)", "rgb(255, 255, 0)", "rgb(0, 255, 0)",
        "rgb(0, 255, 255)", "rgb(74, 134, 232)", "rgb(0, 0, 255)", "rgb(153, 0, 255)", "rgb(255, 0, 255)"
      ],
      ["rgb(230, 184, 175)", "rgb(244, 204, 204)", "rgb(252, 229, 205)", "rgb(255, 242, 204)", "rgb(217, 234, 211)",
        "rgb(208, 224, 227)", "rgb(201, 218, 248)", "rgb(207, 226, 243)", "rgb(217, 210, 233)", "rgb(234, 209, 220)",
        "rgb(221, 126, 107)", "rgb(234, 153, 153)", "rgb(249, 203, 156)", "rgb(255, 229, 153)", "rgb(182, 215, 168)",
        "rgb(162, 196, 201)", "rgb(164, 194, 244)", "rgb(159, 197, 232)", "rgb(180, 167, 214)", "rgb(213, 166, 189)",
        "rgb(204, 65, 37)", "rgb(224, 102, 102)", "rgb(246, 178, 107)", "rgb(255, 217, 102)", "rgb(147, 196, 125)",
        "rgb(118, 165, 175)", "rgb(109, 158, 235)", "rgb(111, 168, 220)", "rgb(142, 124, 195)", "rgb(194, 123, 160)",
        "rgb(166, 28, 0)", "rgb(204, 0, 0)", "rgb(230, 145, 56)", "rgb(241, 194, 50)", "rgb(106, 168, 79)",
        "rgb(69, 129, 142)", "rgb(60, 120, 216)", "rgb(61, 133, 198)", "rgb(103, 78, 167)", "rgb(166, 77, 121)",
        "rgb(91, 15, 0)", "rgb(102, 0, 0)", "rgb(120, 63, 4)", "rgb(127, 96, 0)", "rgb(39, 78, 19)",
        "rgb(12, 52, 61)", "rgb(28, 69, 135)", "rgb(7, 55, 99)", "rgb(32, 18, 77)", "rgb(76, 17, 48)"
      ]
    ]
  });
 var...