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HTML

            
              <h1 id="title">HSL PREVIEW</h1>
<div id="container">
  <div class="range_slider">
    <input id='range1' type="range" value="276" min="0" max="360" step="3">
    <span id='val1' class="rval">276</span>
  </div>
  <div class="range_slider">
    <input id='range2' type="range" value="100" min="0" max="100">
    <span id='val2' class="rval">100</span>
  </div>
  <div class="range_slider">
    <input id='range3' type="range" value="6" min="0" max="100">
    <span id='val3' class="rval">6</span>
  </div>
</div>
!

CSS

            
              :root {
  --title: hsla(210, 19%, 40%, 0.5);
  --slider: hsl(210, 19%, 40%);
  --track: hsl(241, 19%, 48%);
}

* {
  text-align: center;
  font-family: Arial;
  box-sizing: border-box;
}

body {
  margin: 50px calc(20% + 20px) 50px 20%;
}

#title {
  font-size: 1.6rem;
  margin: 80px 25px 20px 0;
  color: var(--title);
  filter:saturate(10);
}

.range_slider {
  margin: 50px 0;
  width: 100%;
}

input {
  margin: 0;
  height: 25px;
  width: calc(100% - (100px));
  background: transparent;
}

div .rval,
input,
input::-moz-range-track {
  border-radius: 5px;
}

input::-moz-range-track {
  background: var(--track);
  border: solid 4px var(--track);
 box-shadow: 2px 4px 8px 0 hsla(241, 19%, 32%, 0.6);
}

input::-webkit-slider-thumb {
  appearance: none;
  -moz-appearance: none;
  -webkit-appearance: none;
}

input::-moz-range-thumb {
  --size: 30px;
  width: var(--size);
  height: var(--size);
  background: var(--slider);
  border: 1px solid var(--slider);
  cursor: pointer;
}

.rval {
  width: 60px;
  padding: 5px 10px;
  margin: 20px 0 20px 20px;
  position: relative;
  display: inline-block;
  color: white;
  background: var(--slider);
 box-shadow: 2px 4px 8px 0 hsla(241, 19%, 32%, 0.6);
} 

.rval:after {
  width: 0;
  height: 0;
  top: 8px;
  left: -8px;
  position: absolute;
  border-top: 8px solid transparent;
  border-right: 8px solid var(--slider);
  border-bottom: 8px solid transparent;
  content: '';
}

.pulse {
  animation: pulse 200ms ease-in-out 2 alternate;
  }

@keyframes pulse {
  from {
    transform: scale(1);
  }

  to {
    transform: scale(1.2);
  }
}

@media screen and (min-width: 800px) {
  #title {
    font-size: 2.3rem;
  }
}

@media screen and (min-width: 950px) {
  #title {
    font-size: 2.75rem;
  }
}
!

JS

            
              const body = document.body;
body.style.background = `hsl(276, 100%, 6%)`;


const getVals = () => ([range1, range2, range3]).map(item => item.value);

const updateValue = (values) => {
  const [v1, v2, v3] = values;
  return [val1.textContent, val2.textContent, val3.textContent] = [v1, v2, v3];
}

const updateColor = (values) => {
  const [v1, v2, v3] = values;
  const color = `hsl(${v1}, ${v2}%, ${v3}%)`;
  return body.style.background = title.textContent = color;
}

const autoContrast = (value) => {
  let [r, g, b] = value.match(/\d+/g);
  [r, g, b] = [r * 0.2126, g * 0.7152, b * 0.0722];
  title.style.color = (r + g + b) >= 128 ? "hsla(261,23%,38%,0.6)" : "hsla(225,100%,92%,0.6)";
}


container.addEventListener("input", (e) => {
  if (e.target && e.target.nodeName == "INPUT") {
    const values = getVals();
    updateValue(values);
    updateColor(values);
    autoContrast(body.style.background);
  }
});


const copyText = () => {
  const el = document.createElement('textarea');
  el.value = title.textContent;
  el.setAttribute('readonly', "");
  el.style.position = 'absolute';
  el.style.left = '-9999px';
  body.appendChild(el);
  const selected = document.getSelection().rangeCount > 0 ? document.getSelection().getRangeAt(0) : false;
  el.select();
  document.execCommand('copy');
  body.removeChild(el);
  if (selected) {
    document.getSelection().removeAllRanges();
    document.getSelection().addRange(selected);
  }
}

title.addEventListener("click", (e) => {
  if (title.textContent !== "HSL PREVIEW") {
    title.className = "pulse";
    copyText();
    title.addEventListener("animationend", (e) => {
      title.className = "";
    }, false);
  }
}, false);
!
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