Fluid Text, Fluid Typography - CSS

The following code scale font-size from a minimum of 16px (at a 320px viewport) to a maximum of 22px (at a 1000px viewport).

CSS

html {
  font-size: 16px;
}
@media screen and (min-width: 320px) {
  html {
    font-size: calc(16px + 6 * ((100vw - 320px) / 680));
  }
}
@media screen and (min-width: 1000px) {
  html {
    font-size: 22px;
  }
}

More – https://css-tricks.com/snippets/css/fluid-typography/

Fluid Text, Fluid Typography – CSS

CSS