Flexible font sizes

flexible-font-sizes-mixin.scss

@function strip-unit($value) {
	@return $value / ($value * 0 + 1);
}

@mixin flexible_font_sizes( $min-font-size, $max-font-size, $min-width, $max-width ) {

	$font-size-difference: strip-unit($max-font-size - $min-font-size);
	$viewport-difference: strip-unit($max-width - $min-width);

	@media screen and #{breakpoint($min-width)} and #{breakpoint($max-width down)} {
		font-size: calc( #{$min-font-size} + #{$font-size-difference} * ( ( 100vw - #{$min-width} ) / #{$viewport-difference} ) );
	}

}

.module-with-flexible-sizes {
	@include flexible_font_sizes( 16px, 20px, 320px, 539px );
}