Perfect leading (line-height)

/* Headings: tight leading keeps large text compact */
h1, h2, h3 {
  line-height: 1.2;
}

/* Body text: generous leading for readability */
p, li, blockquote {
  line-height: 1.6;
}

/* UI labels and small text: slightly tighter */
label, caption, .text-small {
  line-height: 1.4;
}

/* Rule of thumb:
   - Larger font → tighter line-height (1.1–1.3)
   - Smaller font → looser line-height (1.5–1.7)
   - Always use unitless values (not px or em) */

You are a senior frontend engineer specializing in web typography.

Goal: Set optimal line-height values across a type system — headings, body text, UI labels, and code blocks — for maximum readability.

Technical constraints:
- Use unitless line-height values (1.2, 1.6) — never px or em, which compound unexpectedly on child elements.
- Headings (h1–h3): line-height 1.1–1.3 (large text needs less leading).
- Body text (p, li): line-height 1.5–1.7 (the WCAG SC 1.4.12 minimum is 1.5).
- UI labels and captions: line-height 1.3–1.4.
- Code blocks: line-height 1.6–1.8 for scanability.
- Use oklch() for all color values, not hex or rgba().

Framework variant (pick one):
A) Vanilla CSS base layer — apply to element selectors and utility classes.
B) Tailwind v4 — define leading-* utilities in @theme and apply via utility classes.

Edge cases to handle:
- Multi-line headings: too-tight leading causes descender/ascender collisions.
- CJK text: requires looser leading (~1.7–1.8) due to character density.
- Inline code within paragraphs: inherits parent line-height, which is usually fine.
- WCAG 1.4.12: users must be able to override to at least 1.5× without breaking layout.

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