Sass/SCSS function to convert from px to rem

style.scss

/* Usage -- font-size: rem(16) */

@use 'sass:math';

@function rem($pixel) {
  @if math.is-unitless($pixel) {
    @return math.div($pixel, 16) + rem;
  } @else {
    @error 'Don\'t use units when using the rem() function; only numbers.';
  }
}