Precise control over responsive typography for Sass

Fluid typography using viewport units

// Source - https://www.smashingmagazine.com/2016/05/fluid-typography/

// ----
// libsass (v3.5.0.beta.2)
// ----

// =========================================================================
//
//  PRECISE CONTROL OVER RESPONSIVE TYPOGRAPHY FOR SASS
//  ---------------------------------------------------
//  Indrek Paas @indrekpaas
//
//  Inspired by Mike Riethmuller's Precise control over responsive typography
//  http://madebymike.com.au/writing/precise-control-responsive-typography/
//
//  Borrowed `strip-unit` function from Hugo Giraudel
//  https://css-tricks.com/snippets/sass/strip-unit-function/
//
//  02.04.2018 Remove `screen` keyword from media queries
//  11.08.2016 Remove redundant `&` self-reference
//  31.03.2016 Remove redundant parenthesis from output
//  02.10.2015 Add support for multiple properties
//  24.04.2015 Initial release
//
// =========================================================================

@mixin fluid-type($properties, $min-vw, $max-vw, $min-value, $max-value) {
  @each $property in $properties {
    #{$property}: $min-value;
  }

  @media (min-width: $min-vw) {
    @each $property in $properties {
      #{$property}: calc(#{$min-value} + #{strip-unit($max-value - $min-value)} * (100vw - #{$min-vw}) / #{strip-unit($max-vw - $min-vw)});
    }
  }

  @media (min-width: $max-vw) {
    @each $property in $properties {
      #{$property}: $max-value;
    }
  }
}

@function strip-unit($number) {
  @if type-of($number) == "number" and not unitless($number) {
    @return $number / ($number * 0 + 1);
  }

  @return $number;
}

/* Single property */
html {
  @include fluid-type(font-size, 320px, 1366px, 14px, 18px);
}

/* Multiple properties with same values */
h1 {
  @include fluid-type(padding-bottom padding-top, 20em, 70em, 2em, 4em);
}

SassMeister-output.css

/* Single property */
html {
  font-size: 14px;
}

@media (min-width: 320px) {
  html {
    font-size: calc(14px + 4 * (100vw - 320px) / 1046);
  }
}

@media (min-width: 1366px) {
  html {
    font-size: 18px;
  }
}

/* Multiple properties with same values */
h1 {
  padding-bottom: 2em;
  padding-top: 2em;
}

@media (min-width: 20em) {
  h1 {
    padding-bottom: calc(2em + 2 * (100vw - 20em) / 50);
    padding-top: calc(2em + 2 * (100vw - 20em) / 50);
  }
}

@media (min-width: 70em) {
  h1 {
    padding-bottom: 4em;
    padding-top: 4em;
  }
}