is this the simplest adaptive adaptation scheme for web mobile?

html {
font-size: 62.5%;
font-size:calc (100vw/3.75);
font-size:-webket-calc (100vw/3.75); / Mobile adaptation /
}

what are the benefits and meaning of writing like this?

62.5% and 3.75 in calc (100vw/3.75);?