Ns Line Height

line-height: additive, not the web's line box

line-height in NativeScript does not mean what it means on the web, and the difference only shows on text that wraps — which is why the bug ships: single-line labels look perfect, then a long title wraps and sprouts a giant gap.

The semantics

So a web-normal line-height: 24 on 16dp text renders ~16dp lines plus 24dp of air between them — more gap than text. And a unitless web value like 1.25 becomes a meaningless 1.25dp of extra spacing (visually a no-op).

Default rule: don't set line-height at all. Native text rendering already uses the platform's per-font line spacing — the "correct" look. Reach for line-height only to add deliberate breathing room, and think in dp of extra space (line-height: 4), never in web ratios or rem-derived values.

The Tailwind trap (how this bug enters a codebase)

Tailwind's default fontSize scale ships tuples: text-base = [1rem, { lineHeight: 1.5rem }]. Through @nativescript/tailwind that becomes font-size: 16; line-height: 24 — silently injecting 24dp of extra spacing into every text-base label that wraps. Every text-* utility does this.

Fix at the root — replace the scale with plain sizes in tailwind.config.js so text-* emits only font-size:

theme: {
  fontSize: {
    xs: '12', sm: '14', base: '16', lg: '18', xl: '20',
    '2xl': '24', '3xl': '30', '4xl': '36', '5xl': '48', '6xl': '60',
  },
  extend: {},
}

Note it's theme.fontSize (replace), not theme.extend.fontSize (merge — would keep the tuples).

Don't fix it per-label with leading-none/leading-tight sprinkled wherever wrapping is noticed today: unitless leading-* values are ~no-op dp amounts in NativeScript (they only appear to work by overriding the tuple), and the next wrapped label reintroduces the bug. One config change fixes every current and future label.

Case guide

• Multi-line Label gaps too big (list titles, descriptions with textWrap="true"): remove the line-height — usually by fixing the Tailwind scale above.
• Looks right on one screen, wrong on another: the "right" screen likely has a leading-* utility overriding the tuple with a near-zero dp value. That's masking, not fixing — fix the scale.
• Deliberately airier paragraphs (long-form reading): add explicit dp, e.g. line-height: 4 (≈ +4dp between lines), on that text style only.
• Markdown/rich-text components manage their own paragraph spacing — don't impose an app-wide line-height on their containers.
• Cross-platform check: values are additive on both platforms, so one dp value reads consistently — but always eyeball a wrapped label on both.

Verify

• Find a label that wraps to 2+ lines (or temporarily lengthen its text): the inter-line gap should match the rhythm native text has in the OS's own apps, not paragraph-like air.
• Single-line labels are useless as evidence — line-height has no effect until text wraps.
• Grep the compiled CSS or source for line-height: every remaining occurrence should be an intentional, dp-denominated value with a reason.

Verified 2026-08: iOS 26 simulator + Android 15 emulator, @nativescript/core 9.1.0-alpha.11 with @nativescript/tailwind, in a production app (before/after screenshots of wrapped labels).