Fluid Type on CodePen Blogs

It became more popular to “go fully responsive” with layouts, where widths were largely in percentages, so that you get to use as much room is available at any given screen size. To a point, anyway.

You can also “go fully responsive” with typography, in a sense. There are a number of Pens by Mike Riethmuller that tackle things like fluid type size, fluid modular scale, and even fluid vertical rhythm.

It’s worth reading up on Mike’s technique here, but a distilled Sass version is like:

Code language: Sass

@function strip-unit($value) {
  @return $value / ($value * 0 + 1);
}
 
@mixin fluid-type($min-vw, $max-vw, $min-font-size, $max-font-size) {
  $u1: unit($min-vw);
  $u2: unit($max-vw);
  $u3: unit($min-font-size);
  $u4: unit($max-font-size);
 
  @if $u1 == $u2 and $u1 == $u3 and $u1 == $u4 {
    & {
 
      font-size: $min-font-size;
      @media screen and (min-width: $min-vw) {
        font-size: calc(#{$min-font-size} + #{strip-unit($max-font-size - $min-font-size)} * ((100vw - #{$min-vw}) / #{strip-unit($max-vw - $min-vw)}));
      }
 
      @media screen and (min-width: $max-vw) {
        font-size: $max-font-size;
      }
    }
  }
}
 
$min_width: 320px;
$max_width: 1200px;
$min_font: 16px;
$max_font: 24px;
 
$mod_1: 1.2; // mobile
$mod_2: 1.5; // desktop
 
html {
  @include fluid-type($min_width, $max_width, $min_font, $max_font);
}
 
h1 {  
  font-size: $mod_1*$mod_1*$mod_1*$mod_1 *1rem; 
  @include fluid-type($min_width, $max_width, $mod_1*$mod_1*$mod_1 *$min_font, $mod_2*$mod_2*$mod_2 *$min_font);
}
h2 {  
  font-size: $mod_1*$mod_1*$mod_1 *1rem; 
  @include fluid-type($min_width, $max_width, $mod_1*$mod_1*$mod_1 *$min_font, $mod_2*$mod_2*$mod_2 *$min_font);
}
h3 { 
  font-size: $mod_1*$mod_1 *1rem;
  @include fluid-type($min_width, $max_width, $mod_1*$mod_1 *$min_font, $mod_2*$mod_2 *$min_font);
}