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CSS

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HTML 

              
                <h1 class="title">Typography ⌨️ Playground </h1>

<div class="container">

  <h2>Recommendations</h2>
  <ul>
    <li>Font Size: 16px to 26px</li>
    <li>Line-Height: 120% to 160%</li>
    <li>Line-Length: 45 to 90 characters (including spaces)</li>
  </ul>
  <article class="paper">
    <div class="slide-container">
      <p class="input-description">Font&nbsp;Size</p>
      <input type="range" min="8" max="42" value="19" class="slider" id="font-size-slider">
      <p class="input-result" id="font-size-value">19px</p>
    </div>

    <div class="slide-container">
      <p class="input-description">Line&nbsp;Height</p>
      <input type="range" min="50" max="300" value="150" class="slider" id="line-height-slider">
      <p class="input-result" id="line-height-value">150%</p>
    </div>
    <div class="slide-container">
      <p class="input-description">Line&nbsp;Length</p>
      <input type="range" min="0" max="15" value="0" class="slider" id="line-length-slider">
      <p class="input-result" id="line-length-value">160%</p>
    </div>

    <hr style="margin: 1em 0; color: #333; opacity: .5; ">

    <p class="demo-text" style="font-size: 19px; line-height: 1.5">The main part of this book was written during the dark days of the war, and this preface, cogitated during days which were darker still. During the war we could dream of peace, and we thought of it as if it would bring happiness and virtue. That would
      have been possible if the greed for material things and for power had subsided, but it has not by any means, and in a sense one might say that the war is not over. Our technicians are arranging a new world free from the humanities, with a few atomic
      bombs suspended above it. They seem to think that when bread has been given to the people, the essential has been done, but man cannot live by bread alone. (Millions of men and women lack even bread.) Nevertheless, we should not despair, but work
      harder, with a deeper faith, cultivate the humanities, and defend the noble traditions without which life, however efficient or comfortable, is hardly worth living.</p>

  </article>
</div>
<!-- End  -->
!

CSS 

              
                /**
 * index.scss
 * - Add any styles you want here!
 */
* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}



$font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica,
  Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol";
$font-serif: Georgia, "Times New Roman", serif;

body {
  background: #cccccc;

  font-family: $font-serif;
  font-size: calc(1em + 0.35vw);
  line-height: 1.5;
}

h1 {
  margin: 0.5em 1em;
  color: #333;
  // color: scale-color(#6b5b95, $lightness: -30%);
  font-family: $font-sans;
  font-size: 2.5em;
  font-weight: 700;
  letter-spacing: 2px;
  line-height: 1.2;
  text-align: center;
  text-shadow: 1px 1px #fbaf08, 2.5px 2.5px #333;
  text-transform: uppercase;
}

h2 {
  font-family: $font-sans;
  font-size: 1.5em;
  font-weight: 600;
}

%margin-tb {
  margin: 0.5em 0;
}

%page-padding {
  margin: 0 auto;
  max-width: 1040px;
  padding: 1em 4vw;
}

.slide-container {
  width: 100%;

  align-items: center;
  display: flex;
  flex-shrink: 1;
  flex-wrap: wrap;

  margin-bottom: 1em;
}

.input-description,
.input-result {
  margin: 0.5em 0;

  font-family: $font-sans;
  line-height: 1.1;
  text-transform: uppercase;
  font-weight: 600;
}

.input-description {
  margin-right: 25px;
  width: 6em;
}

.input-result {
  width: 3em;
  text-align: left;
}

.slider {
  -webkit-appearance: none;
  appearance: none;
  flex: 100%;
  height: 10px;
  margin: 0.5em 0;
  background: #4d4d4d;
  border-radius: 10px;
  outline: none;
  opacity: 0.7;
  -webkit-transition: 0.2s;
  transition: opacity 0.2s;
}

@media screen and (min-width: 480px) {
  .slider {
    flex: 2;
  }
  .input-result {
    margin-left: 25px;
    text-align: right;
  }
}

.slider::-webkit-slider-thumb {
  -webkit-appearance: none; /* Override default look */
  appearance: none;
  width: 25px; /* Set a specific slider handle width */
  height: 25px; /* Slider handle height */
  background: #4d4d4d; /* Green background */
  border-radius: 50%;
  cursor: grab; /* Cursor on hover */
  line-height: 1;
}

.slider::-moz-range-thumb {
  width: 25px; /* Set a specific slider handle width */
  height: 25px; /* Slider handle height */
  background: #4d4d4d; /* Green background */
  cursor: grab; /* Cursor on hover */
  border-radius: 50%;
  border: 2px solid black;
  line-height: 1;
  box-shadow: 8px 8px 15px rgba(0, 0, 0, 0.08), 1px 1px 2px rgba(0, 0, 0, 0.15);
  
}

.slider::-moz-range-thumb:active {
  cursor: grabbing;
}

.slider::-webkit-slider-thumb:active {
  cursor: grabbing; 
}

#font-size-value {
  text-transform: lowercase;
}

.paper {
  height: 1000px;

  margin: 2em 0;
  padding: 2em 2em;

  background: #ddd;
  border-radius: 10px;
  box-shadow: 8px 8px 15px rgba(0, 0, 0, 0.08), 1px 1px 2px rgba(0, 0, 0, 0.15);
  overflow: hidden;
}

.container {
  @extend %page-padding;
}

.identifier {
  margin-bottom: 1em;
  padding: 5px;
  font-size: calc(1em + 0.35vw);
  font-family: $font-sans;
  border-bottom: 3px solid #66806d;
  .right {
    float: right;
  }
}
!

JS 

              
                // Get demo text
const demoText = document.querySelector(".demo-text");

// Get Font Size slider and value
const fontSizeSlider = document.getElementById("font-size-slider");
const fontSizeValue = document.getElementById("font-size-value");

// Get Line Height
const lineHeightSlider = document.getElementById("line-height-slider");
const lineHeightValue = document.getElementById("line-height-value");

// Set font size and value on change
fontSizeSlider.addEventListener("input", e => {
  demoText.style.fontSize = `${e.target.value}px`;
  fontSizeValue.innerText = `${e.target.value}px`;
});

// Set line height and value on change
lineHeightSlider.addEventListener("input", e => {
  demoText.style.lineHeight = `${e.target.value}%`;
  lineHeightValue.innerText = `${e.target.value}%`;
});

//Calculate line height and words per line
const demoStyles = document.defaultView.getComputedStyle(demoText);
const inputs = document.querySelectorAll("input");
const wordsPerLine = document.getElementById("line-length-value");

function updateLines() {
  let height = parseInt(demoStyles.getPropertyValue("height"));
  let lineHeight = parseInt(demoStyles.getPropertyValue("line-height"));
  let result = height / lineHeight;
  let characterCount = demoText.innerText.length;
  let lineResult = Math.round(characterCount / result);
  wordsPerLine.innerText = lineResult;
}

updateLines();

inputs.forEach(item => {
  item.addEventListener("input", updateLines);
});

// Update line length value
const lineLengthSlider = document.getElementById("line-length-slider");

lineLengthSlider.addEventListener("input", e => {
  demoText.style.padding = `0 ${e.target.value}em`;
});
!
999px

Console