$fibonacci-sequence: 1, 2, 3, 5, 8, 13, 21, 34, 55;
$min-breakpoint: 22.5; // = 360px
$max-breakpoint: 80;   // = 1280px

/**
 * Font size scale based on the harmonic sequence.
 */
$font-size-scale: calc(var(--_harmonic-sequence-base) / (var(--_harmonic-sequence-base) - var(--_font-size-level)));

/**
 * Font size formula.
 */
$font-size: calc(#{ $font-size-scale } * 1rem);

$_max-font-size: calc(var(--_max-harmonic-sequence-base) / (var(--_max-harmonic-sequence-base) - var(--_font-size-level)));
$_min-font-size: calc(var(--_min-harmonic-sequence-base) / (var(--_min-harmonic-sequence-base) - var(--_font-size-level)));
$_slope: calc((#{ $_max-font-size } - #{ $_min-font-size }) / (#{ $max-breakpoint - $min-breakpoint }));
$_yAxis: calc(#{-1 * $min-breakpoint } * #{ $_slope } + #{ $_min-font-size });
$_preferred-font-size: calc((#{ $_yAxis } * 1rem) + (#{ $_slope } * 100vw));
$fluid-font-size: clamp(1rem * #{ $_min-font-size }, #{ $_preferred-font-size }, 1rem * #{ $_max-font-size });

/**
 * Line height formula.
 */
$line-height: clamp(
  1.1,
  calc(var(--_line-height-slope) * #{ $font-size-scale } + 1 + 2 * var(--_half-leading) + -1 * var(--_line-height-slope)),
  calc(2 * var(--_half-leading) + 1)
);