font-mixins.scss

@function em($from, $to, $dimension: true) {
  @return ($from / $to) * if($dimension, 1em, 1);
}

@function rem($px, $root: 16px) {
  @return ($px / $root) * 1rem;
}

@mixin font($font-size, $line-height: null) {
  font-size: rem($font-size);
  line-height: if($line-height, em($line-height, $font-size, false), null);
}