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HTML

CSS

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HTML

              
                <h1>This font resizes fluidly in evergreen browsers</h1>
<p>The font scale is between 14px and 18px, which applies in between 1280px and 1920px window width.</p>
<p>I have used em-units in the code solely out of preference.</p>

              
            
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CSS

              
                html {
  font-size: 0.875em;
}

/**
 * 1. Apply rule to all browsers
 * 2. Override WebKit browsers, because Safari needs percentages to work
 * 3. Override IE/Edge, because Edge applies previous -webkit-calc() and 
 *    won't work with percentages
 */
@media screen and (min-width: 80em) {
  html {
    font-size: calc(0.875em + 0.25 * (100vw - 80em) / 40); /* 1 */
    font-size: -webkit-calc(87.5% + 0.25 * (100vw - 8000%) / 40); /* 2 */
    font-size: -ms-calc(0.875em + 0.25 * (100vw - 80em) / 40); /* 3 */
  }
}

@media screen and (min-width: 120em) {
  html {
    font-size: 1.125em;
  }
}

              
            
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JS

              
                
              
            
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999px

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