Generated by SassMeister.com.

SassMeister-input.scss

// ----
// libsass (v3.2.5)
// ----

$p-font-sizes: (
  null  : 15px,
  480px : 16px,
  640px : 17px,
  1024px: 19px
);

$h1-font-sizes: (
  null  : 28px,
  480px : 31px,
  640px : 33px,
  1024px: 36px
);

@mixin font-size($fs-map) {
  @each $fs-breakpoint, $fs-font-size in $fs-map {
    @if $fs-breakpoint == null {
      font-size: $fs-font-size;
    }
    @else {
      @media screen and (min-width: $fs-breakpoint) {
        font-size: $fs-font-size;
      }
    }
  }
}

h1 {
  @include font-size($h1-font-sizes);
}

p, ul, ol {
  @include font-size($p-font-sizes);
}

SassMeister-output.css

h1 {
  font-size: 28px;
}

@media screen and (min-width: 480px) {
  h1 {
    font-size: 31px;
  }
}

@media screen and (min-width: 640px) {
  h1 {
    font-size: 33px;
  }
}

@media screen and (min-width: 1024px) {
  h1 {
    font-size: 36px;
  }
}

p, ul, ol {
  font-size: 15px;
}

@media screen and (min-width: 480px) {
  p, ul, ol {
    font-size: 16px;
  }
}

@media screen and (min-width: 640px) {
  p, ul, ol {
    font-size: 17px;
  }
}

@media screen and (min-width: 1024px) {
  p, ul, ol {
    font-size: 19px;
  }
}