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Adding Classes

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CSS

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JavaScript

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HTML 

              
                <h1 class="title">Homage to the Square</h1>
  <p>
    Based on the series of paintings by
    <a class="link" href="https://en.wikipedia.org/wiki/Josef_Albers">Josef Albers</a>.
  </p>
  <p>
    <a class="link" href="https://codepen.io/ramonmcros/pen/yNEeNo">CodePen</a> || <a class="link" href="https://github.com/ramonmcros/homage-to-the-square" target="_blank">GitHub</a>
  </p>
  <canvas id="homage" width="632" height="632"></canvas>
  <form class="controls">
    <fieldset class="group" action="index.html" method="post">
      <legend>First Square</legend>
      <label for="first-hue">Hue</label>
      <input type="range" id="first-hue" name="first-hue" min="0" value="7" max="360">
      <label for="first-saturation">Saturation</label>
      <input type="range" id="first-saturation" name="first-saturation" min="0" value="66" max="100">
      <label for="first-lightness">Lightness</label>
      <input type="range" id="first-lightness" name="first-lightness" min="0" value="82" max="100">
    </fieldset>
    <fieldset class="group" action="index.html" method="post">
      <legend>Second Square</legend>
      <label for="second-hue">Hue</label>
      <input type="range" id="second-hue" name="second-hue" min="0" value="21" max="360">
      <label for="second-saturation">Saturation</label>
      <input type="range" id="second-saturation" name="second-saturation" min="0" value="98" max="100">
      <label for="second-lightness">Lightness</label>
      <input type="range" id="second-lightness" name="second-lightness" min="0" value="68" max="100">
    </fieldset>
    <fieldset class="group" action="index.html" method="post">
      <legend>Third Square</legend>
      <label for="third-hue">Hue</label>
      <input type="range" id="third-hue" name="third-hue" min="0" value="27" max="360">
      <label for="third-saturation">Saturation</label>
      <input type="range" id="third-saturation" name="third-saturation" min="0" value="99" max="100">
      <label for="third-lightness">Lightness</label>
      <input type="range" id="third-lightness" name="third-lightness" min="0" value="58" max="100">
    </fieldset>
    <fieldset class="group" action="index.html" method="post">
      <legend>Fourth Square</legend>
      <label for="fourth-hue">Hue</label>
      <input type="range" id="fourth-hue" name="fourth-hue" min="0" value="23" max="360">
      <label for="fourth-saturation">Saturation</label>
      <input type="range" id="fourth-saturation" name="fourth-saturation" min="0" value="99" max="100">
      <label for="fourth-lightness">Lightness</label>
      <input type="range" id="fourth-lightness" name="fourth-lightness" min="0" value="57" max="100">
    </fieldset>
    <a href="#" id="save" class="save">Save</a>
  </form>
!

CSS 

              
                @import url(https://fonts.googleapis.com/css?family=Droid+Sans:400,700);

$cloud: #c5c5d0;
$dark-cloud: darken($cloud, 40%);
$darkest-cloud : darken($dark-cloud, 20%);

html {
  box-sizing: border-box;
}
*, *:before, *:after {
  box-sizing: inherit;
}

body {
  color: $dark-cloud;
  font-family: 'Droid Sans', sans-serif;
  font-size: 18px;
  padding: 0 24px;
}

p {
  text-align: center;
}

.link {
  text-decoration: none;
  color: $darkest-cloud;

  &:hover {
    border-bottom: 2px solid $darkest-cloud;
    padding-bottom: 1px;
  }
}

.controls {
  display: flex;
  justify-content: center;
  flex-wrap: wrap;
  width: 50%;
  padding: 40px 0 40px 15px;

  @media all and (max-width: 900px) {
    width: 100%;
    padding: 40px 0;
  }

  @media all and (max-width: 500px) {
    padding: 15px 0;
    font-size: 16px;
  }
}

.title {
  display: block;
  width: 100%;
  font-size: 48px;
  text-align: center;
  margin-bottom: 30px;
}

.group {
  border: none;
  padding: 15px;
  width: 50%;
  margin: 0 0 10px;

  legend {
    font-weight: bold;
    text-align: center;
    width: 100%;
  }

  input {
    display: block;
  }

  label {
    display: block;
    text-align: center;
    margin-top: 15px;

    &[for*="hue"] {
      margin-top: 0;
    }
  }
}

#homage {
  width: 50%;
  padding: 40px 15px;
  float: left;

  @media all and (max-width: 900px) {
    width: 100%;
    float: none;
    max-width: 632px;
    margin: 0 auto;
    display: block;
  }

  @media all and (max-width: 500px) {
    padding: 15px 0;
  }
}

.save {
  margin: 30px 0;
  color: white;
  background-color: $dark-cloud;
  padding: 10px 25px;
  text-decoration: none;
  text-align: center;

  &:hover {
    background: $darkest-cloud;
  }

  @media all and (max-width: 500px) {
    margin-top: 0;
  }
}

/* *
 * Sliders
 */

input[type=range] {
  -webkit-appearance: none;
  width: 100%; /* Specific width is required for Firefox. */
}

input[type=range]::-webkit-slider-thumb {
  -webkit-appearance: none;
}

input[type=range]:focus {
  outline: none;
}

input[type=range]::-ms-track {
  cursor: pointer;
  background: transparent;
  border-color: transparent;
  color: transparent;
  margin: 10px 0;
}

input[type=range]::-webkit-slider-thumb {
  height: 9px;
  width: 9px;
  border-radius: 50%;
  background: $dark-cloud;
  margin-top: -3px;

}

input[type=range]:active::-webkit-slider-thumb {
  height: 15px;
  width: 15px;
  margin-top: -6px;
}

input[type=range]::-webkit-slider-runnable-track {
  width: 100%;
  height: 3px;
  cursor: pointer;
  background: $cloud;
  margin: 10px 0;
}

input[type=range]:focus::-webkit-slider-runnable-track {
  background: $cloud;
}

input[type=range]::-moz-range-thumb {
  height: 9px;
  width: 9px;
  border-radius: 50%;
  background: $dark-cloud;
  border: none;
}

input[type=range]:active::-moz-range-thumb {
  height: 15px;
  width: 15px;
}

input[type=range]::-moz-range-track {
  background-color: $cloud;
  height: 3px;
}

input[type=range]::-ms-thumb {
  height: 9px;
  width: 9px;
  background: $dark-cloud;
  border: none;
  border-radius: 50%;
}

input[type=range]::-ms-track {
  width: 100%;
  height: 3px;
  cursor: pointer;
  background: $cloud;
}

input[type=range]::-ms-fill-lower {
  background: $cloud;
}
input[type=range]:focus::-ms-fill-lower {
  background-color: $cloud;
}
input[type=range]::-ms-fill-upper {
  background-color: $cloud;
}
input[type=range]:focus::-ms-fill-upper {
  background-color: $cloud;
}
!

JS 

              
                window.onload = function() {
  var homage = document.getElementById('homage');
  context = homage.getContext('2d');

  // First square HSL color variables
  var firstHue = document.getElementById('first-hue');
  var firstSaturation = document.getElementById('first-saturation');
  var firstLightness = document.getElementById('first-lightness');
  // Second square HSL color variables
  var secondHue = document.getElementById('second-hue');
  var secondSaturation = document.getElementById('second-saturation');
  var secondLightness = document.getElementById('second-lightness');
  // Third square HSL color variables
  var thirdHue = document.getElementById('third-hue');
  var thirdSaturation = document.getElementById('third-saturation');
  var thirdLightness = document.getElementById('third-lightness');
  // Fourth square HSL color variables
  var fourthHue = document.getElementById('fourth-hue');
  var fourthSaturation = document.getElementById('fourth-saturation');
  var fourthLightness = document.getElementById('fourth-lightness');

  var save = document.getElementById('save');

  var passHSL = function(hue, saturation, lightness) {
    return 'hsl(' + hue.value + ', ' + saturation.value + '%, ' + lightness.value + '%)';
  };

  function firstSquare() {
    var colorFirst = passHSL(firstHue, firstSaturation, firstLightness);
    context.fillStyle = colorFirst;
    context.fillRect(0, 0, 632, 632);
    firstHue.addEventListener('input', firstSquare);
    firstSaturation.addEventListener('input', firstSquare);
    firstLightness.addEventListener('input', firstSquare);
    secondSquare();
  }

  function secondSquare() {
    var colorSecond = passHSL(secondHue, secondSaturation, secondLightness);
    context.fillStyle = colorSecond;
    context.fillRect(62, 96, 508, 508);
    secondHue.addEventListener('input', secondSquare);
    secondSaturation.addEventListener('input', secondSquare);
    secondLightness.addEventListener('input', secondSquare);
    thirdSquare();
  }

  function thirdSquare() {
    var colorThird = passHSL(thirdHue, thirdSaturation, thirdLightness);
    context.fillStyle = colorThird;
    context.fillRect(124, 192, 384, 384);
    thirdHue.addEventListener('input', thirdSquare);
    thirdSaturation.addEventListener('input', thirdSquare);
    thirdLightness.addEventListener('input', thirdSquare);
    fourthSquare();
  }

  function fourthSquare() {
    var colorFourth = passHSL(fourthHue, fourthSaturation, fourthLightness);
    context.fillStyle = colorFourth;
    context.fillRect(186, 288, 260, 260);
    fourthHue.addEventListener('input', fourthSquare);
    fourthSaturation.addEventListener('input', fourthSquare);
    fourthLightness.addEventListener('input', fourthSquare);
  }

  firstSquare();

  save.addEventListener('click', function(evt) {
    this.href = homage.toDataURL();
    this.download = 'homage-to-the-square.png';
  }, false);

};
!
999px

Console