<div class="container range__opsz">


  <div class="paragraph">

    <div class="text">Optical Size</div>

  </div>
  <div id='demo-controls' class="controls">
    <div class="value-tag"></div>
    <div class="low-value"></div>
    <div class="slider range-width">
      <input type="range" name="range-opsz" value="80" id="text-vf-opsz" class="controls--opsz" min="8" max="144"> <label for="controls__width">Optical Size</label>
    </div>
    <div class="high-value"></div>
    <div class="current-value"></div>

  </div>

</div>

/* Amstelvar Variable Font */
@font-face {
  font-family: "Amstelvar VF";
  src: url("https://s3-us-west-2.amazonaws.com/s.cdpn.io/57225/Amstelvar-Roman-VF_copy.woff2")
    format("woff2 supports variations"), url("https://s3-us-west-2.amazonaws.com/s.cdpn.io/57225/Amstelvar-Roman-VF_copy.woff2")
    format("woff2-variations");
  font-display: swap;
  font-weight: 100 900;
  font-stretch: 75% 125%;
}
.range__opsz {
  --text-vf-wght: 400;  
  --text-vf-wdth: 95;
  --text-vf-opsz: 80;
  --value-tag: 'opsz';
  --low-value: 8;
  --current-value: var(--text-vf-opsz);
  --high-value: 144;

  .paragraph {
    background-color: #ffffff;
    margin-left: auto;
    margin-right: auto;
    max-width: 95vw;
    width: 45em;
  }

  .paragraph .text {
    font-family: "Amstelvar VF", serif;
    font-size: 5rem;
    font-weight: var(--text-vf-wght);
    font-stretch: calc( var(--text-vf-wdth) * 1% );
    font-variation-settings: 'opsz' var(--text-vf-opsz);
    line-height: 7rem;
    margin: 0 auto 0 auto;
    text-align: center;
  }


  /* Control buttons */
  .controls {
    display: grid;
    grid-template-columns: min-content 1fr min-content;
    margin: 2em auto;
    text-align: center;
    width: 20rem;

    h3 {
      display: inline;
      font-weight: normal;
      font-family: monospace;
    }
    label {
      float: left;
      height: 1px;
      text-indent: -999em;
      visibility: hidden;
    }
    .slider {
      grid-column: 2/3;
      input {
        width: 100%;
      }
    }
    .value-tag {
      grid-column: span 3;
      font-weight: bold;
      margin-bottom: 0.5rem;
      text-align: left;
      &::before {
        counter-reset: tag var(--value-tag);
        content: "'" var(--value-tag) "' range";
        font-family: sans-serif;
      }
   }
    .low-value {
      grid-column: 1/2;
      text-align: left;
      width: 2.5rem;
      &::before {
        counter-reset: tag var(--low-value);
        content: counter(tag);
        font-family: sans-serif;
      }
    }
    .high-value{
      grid-column: 4/5;
      text-align: right;
      width: 2.5rem;
    &::before {
       counter-reset: tag var(--high-value);
       content: counter(tag);
       font-family: sans-serif;
      }
    }
    .current-value {
      grid-column: 2/3;
      &::before {
        counter-reset: tag var(--current-value);
        border: solid 1px black;
        content: counter(tag);
        display: inline-block;
        font-family: sans-serif;
        min-width: 3rem;
        margin: 0 auto;
        padding: 0.25rem 0.25rem 0.2rem 0.25rem;
      }
    }
  }
}

// get the inputs
const inputs = [].slice.call(document.querySelectorAll('.range__opsz .controls input'));

// listen for changes
inputs.forEach(input => input.addEventListener('change', handleUpdate));
inputs.forEach(input => input.addEventListener('mousemove', handleUpdate));


function handleUpdate(e) {      document.querySelector('.range__opsz').style.setProperty(`--${this.id}`, this.value);
}