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CSS

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HTML 

              
                <div class="controls">
  <label for="spacing">
    <a href="https://www.poetryfoundation.org/poetrymagazine/poems/12744/trees">
        I think that I shall never see <br>
    An SVG as lovely as a tree.
      
    </a>
  </label>
    <input id="leafColors" type="range" name="spacing" min="10" max="400" value="10" data-sizing="px" list="months">
    <datalist id="months">
      <option value="50" label="May">
      <option value="100" label="June">
      <option value="150" label="July">
      <option value="200" label="August">
      <option value="250" label="September">
      <option value="300" label="October">
      <option value="350" label="November">
      <option value="400" label="December">
    </datalist>
</div>

<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" version="1.1" x="0px" y="0px" viewBox="0 0 100 125" enable-background="new 0 0 100 100" xml:space="preserve">
  <g>
    <path class="trunk" d="M54.061,63.392c-0.044-1.116-0.344-3.345,1.392-5.507c4.576-5.702,8.979-10.163,9.253-26.052   c-1.148,10.625-4.061,18.225-10.284,21.92c-0.364,0.216-1.123,0.68-1.225-0.8c-0.704-10.068-1.078-21.004-1.91-31.592   c-0.964,12.27-1.281,25.139-2.253,36.321c-0.125,1.434-0.513,2.274-2.038,1.383c-3.459-2.018-8.333-9.051-10.919-19.509   c0.632,9.769,4.325,19.462,10.077,23.785c2.197,1.651,1.863,3.925,1.782,4.967c-1.039,13.372-3.818,19.055-8.43,23.091   c5.564-2.946,11.455-1.31,11.782,3.6c0.982-5.891,6.546-6.546,11.784-3.6C57.768,86.761,54.692,79.732,54.061,63.392z"/>
    <path class="leaf" d="M59.624,27.335c-1.257,4.608-0.196,9.315,2.493,12.667c0.343-2.577,0.686-8.931,5.496-13.57   c-2.405,5.325-2.748,11.854-2.405,15.116c5.862-1.933,8.098-4.862,9.43-8.384c2.718-7.183,0.304-14.388-1.724-18.667   C65.03,17.198,60.976,22.378,59.624,27.335z"/>
    <path class="leaf" d="M49.726,30.732c-0.15-4.987,1.075-12.031,1.566-14.263c0.352,2.772,1.717,8.932,1.455,13.801   c3.592-3.352,5.124-7.571,5.074-10.628C57.703,12.548,53.767,8.154,50.838,5c-4.955,4.055-7.182,10.036-7.138,15.093   C43.741,24.805,45.755,28.579,49.726,30.732z"/>
    <path class="leaf" d="M35.765,46.866c-0.067-2.616-0.633-7.779-3.653-13.054c1.966,1.362,5.701,5.289,7.169,11.548   c2.75-4.697,2.868-8.492,1.651-11.718c-2.761-7.322-13.295-12.162-17.35-13.514c-2.027,6.083-2.253,15.092,1.576,20.499   C27.318,43.675,30.913,45.594,35.765,46.866z"/>
    <path class="leaf" d="M39.964,24.835c-0.477-2.1-1.495-5.977-2.911-8.204c1.6,1.6,3.26,5.203,4.147,7.581c1.576-3.865,1.314-6.691-0.014-8.717   c-1.836-2.802-5.441-4.152-8.37-4.828c-1.125,2.478-1.721,6.695,0.048,9.696C34.235,22.687,36.641,24.256,39.964,24.835z"/>
    <path class="leaf" d="M21.311,42.143c0,0,2.418,2.048,4.051,4.284c0.379-2.133-0.076-3.719-0.878-5.126c-2.064-3.623-5.632-4.28-7.435-4.505   c-0.225,2.252-0.461,5.413,1.089,7.523c1.435,1.955,3.732,2.977,6.337,3.193C23.942,46.262,22.884,44.062,21.311,42.143z"/>
    <path class="leaf" d="M62.162,12.897c-0.334,2.051-0.578,4.435-0.708,6.202c2.355-1.155,3.577-2.489,4.139-3.883   c1.343-3.333-0.789-5.676-1.914-7.929c-2.479,1.126-5.146,2.932-5.591,5.896c-0.272,1.814,0.336,3.766,2.207,5.763   C60.61,17.852,61.19,15.913,62.162,12.897z"/>
    <path class="leaf" d="M58.377,37.918c-4.922,3.646-6.181,8.337-3.369,12.325c0.582-1.111,1.634-3.48,2.385-7.239   c0.089,3.063-0.633,5.773-1.279,7.492C59.787,48.812,61.793,45.736,58.377,37.918z"/>
    <path class="leaf" d="M46.715,53.582c4.451-6.78,0.429-11.923-2.9-15.315c-3.422,5.512-5.635,12.378,1.583,15.509   c-0.766-2.214-1.219-5.313-0.758-8.99C44.911,48.946,46.025,52.024,46.715,53.582z"/>
    <path class="leaf" d="M81.473,28.237c-2.252,1.801-5.368,4.102-6.618,7.927c-0.531,1.626-0.466,3.499,0.714,5.846   c1.054-1.302,2.916-3.955,3.717-7.28c0,0-0.392,5.152-2.625,7.996c2.096-0.107,3.836-1.276,5.039-3.079   C83.926,36.308,83.276,32.066,81.473,28.237z"/>
    <path class="leaf" d="M59.885,58.378c2.204-1.852,6.702-4.966,12.735-5.72c-3.848,1.268-8.811,5.465-11.493,8.464   c3.969,0.726,8.227,0.374,11.85-1.451c5.097-2.569,8.046-7.557,8.722-15.441c-4.506,0.451-10.846-0.106-16.67,4.055   C62.452,50.125,60.491,53.85,59.885,58.378z"/>
    <path class="leaf" d="M27.804,54.44c4.932,0.724,10.431,3.122,13.923,5.484c-2.878-6.245-6.396-8.743-9.98-9.808   c-5.125-1.523-9.065-1.157-12.445-0.932c0.902,5.182,3.052,9.656,7.223,11.686c4.85,2.362,10.507,2.047,14.061,1.098   C38.21,60.157,33.403,56.776,27.804,54.44z"/>
  </g>
  <text x="0" y="105" font-size="3px" font-weight="bold" font-family="'Helvetica Neue', Helvetica, Arial-Unicode, Arial, Sans-serif">Tree created by Alena Artemova</text>
  <text x="0" y="108" font-size="3px" font-weight="bold" font-family="'Helvetica Neue', Helvetica, Arial-Unicode, Arial, Sans-serif">from the Noun Project</text>
</svg>
!

CSS 

              
                @import url('https://fonts.googleapis.com/css?family=Amatic+SC');

:root {
  --leaf: #9BC53D;
  --trunk: #764134;
  --sky: #DCEDFF;
  --bodytext: #493B2A;
}

body {
  margin: 0;
  background: var(--sky);
  color: var(--bodytext);
  font-family: 'Amatic SC', sans-serif;
}

a {
  text-decoration: none;
  color: var(--leaf);
}

text {
  fill: var(--bodytext);
}

.controls {
  display: flex;
  justify-content: center;
  flex-direction: column;
  align-items: center;
  text-transform: uppercase;
  margin: 30px 0 0;
}

#leafColors {
  width: 400px;
}

.controls label {
  margin-bottom: 10px;
  font-size: 46px;
  text-align: center;
}

svg {
  width: 50%;
  margin: 0 auto;
  display: block;
  min-width: 400px;
}

.leaf {
  fill: var(--leaf);
  transform: translateY(0);
  transition: transform 1s;
}

.leaf.loose {
  transform: translateY(200%);
  transition: transform 1s;
}

.trunk {
  fill: var(--trunk);
}
!

JS 

              
                const control = document.querySelector('#leafColors')
const leaves = document.querySelectorAll('.leaf');

const setLeaf = (color) => {
  document.documentElement.style.setProperty(`--leaf`, color);
}

const loseLeaves = () => {
  leaves.forEach((leaf) => {
    leaf.classList.add('loose');
  })
  control.addEventListener('change', reset);
  return;
}
const reset = () => {
  leaves.forEach((leaf) => {
    leaf.classList.remove('loose');
  })
}

function handleUpdate() {
  const val = this.value
  if (val < 49) {
    setLeaf('#9BC53D');
  } else if (val >= 50 && val < 99) {
    setLeaf('#B2BD7E');
  } else if (val >= 100 && val < 149) {
    setLeaf('#8CAE68');
  } else if (val >= 150 && val < 199) {
    setLeaf('#60992D');
  } else if (val >= 200 && val < 249) {
    setLeaf('#447604');
  } else if (val >= 250 && val < 299) {
    setLeaf('#EA9010');
  } else if (val >= 300 && val < 349) {
    setLeaf('#CD8B76');
  } else if (val >= 350 && val < 385) {
    setLeaf('#493B2A');
  } else if (val >= 386) {
    setLeaf('#493B2A');
  } else {
    loseLeaves();
  }
}

control.addEventListener('change', handleUpdate);
control.addEventListener('mousemove', handleUpdate);
!
999px

Console