$min_width: 300px;
$max_width: 1600px;
$min_font: 16px;
$max_font: 18px;
$mod_1: 1.1; // mobile
$mod_2: 1.75; // desktop

html,
body {
  @include fluid-type($min_width, $max_width, $min_font, $max_font);
}

h1,
.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 * $max_font
  );
}
h2,
.h2 {
  font-size: $mod_1 * $mod_1 * $mod_1 * 1rem;
  @include fluid-type(
    $min_width,
    $max_width,
    $mod_1 * $mod_1 * $min_font,
    $mod_2 * $mod_2 * $max_font
  );
}
h3,
.h3 {
  font-size: $mod_1 * $mod_1 * 1rem;
  @include fluid-type(
    $min_width,
    $max_width,
    $mod_1 * $min_font,
    $mod_2 * $max_font
  );
}
h4,
.h4 {
  font-size: $mod_1 * 1rem;
  @include fluid-type($min_width, $max_width, $min_font, $max_font);
}