Demo about Set Propertys with 'vw', 'vh' unit

http://www.w3.org/TR/css3-values/#viewport-relative-lengths

by Julien Etienne

HTML

<div id="div2"> HELLO</div>

CSS

#div2 {
    width: 50vw;
    height: 50vh;
    font-size: calc(1rem * 5vw + 0.00001rem );
}