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HTML

CSS

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JavaScript

Babel includes JSX processing.

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HTML

              
                    <div class="col one">     
      This example showcases use of (fake) vw unit. While things like width were already easy to tie to width of viewport, other properties, such as padding or font size or border radius were not. You should be able to see a couple of boxes with text, which are supposed to change font size, border width, border radius, and padding in response to viewport width changes.
    </div>
    <div class="col two">
        This example showcases use of (fake) vw unit. While things like width were already easy to tie to width of viewport, other properties, such as padding or font size or border radius were not. You should be able to see a couple of boxes with text, which are supposed to change font size, border width, border radius, and padding in response to viewport width changes.
    </div>
    <div class="col three">
        This column does not use the viewport width scaling, and so does not change (except in width) when the window is resized or device is rotated.
    </div>

              
            
!

CSS

              
                html { position: relative; }
body { font-size: 12px; font-family: sans-serif; margin: 0; padding: 0;}


.col { float: left; width: 33.3%; box-sizing: border-box; }
.col.one { background: #CFF; }
.col.two { background: #FFC; }
.col.three { background: #FCF; font-size: 20px; padding: 50px; }

.one, .two {

  border: solid #666;
  border-width: 10px; border-width: 0.01rem; /*1vw*/
  border-radius: 30px; border-radius: 0.03rem; /*3vw*/
  font-size: 20px; font-size: 0.02rem; /*2vw*/
  padding: 20px; padding: 0.02rem; /*2vw*/
}

              
            
!

JS

              
                (function (doc, win) {
    var docEl = doc.documentElement,
        recalc = function () {
            var clientWidth = docEl.clientWidth;
            if (!clientWidth) return;

            docEl.style.fontSize = clientWidth + 'px';
            docEl.style.display = "none";
            docEl.clientWidth; // Force relayout - important to new Androids
            docEl.style.display = "";
        };

    // Abort if browser does not support addEventListener
    if (!doc.addEventListener) return;

    // Test rem support
    var div = doc.createElement('div');
    div.setAttribute('style', 'font-size: 1rem');

    // Abort if browser does not recognize rem
    if (div.style.fontSize != "1rem") return;

    win.addEventListener('resize', recalc, false);
    doc.addEventListener('DOMContentLoaded', recalc, false);
})(document, window);
              
            
!
999px

Console