122 lines
4.7 KiB
Markdown
122 lines
4.7 KiB
Markdown
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# Typography craft rules
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Universal typography rules that apply on top of any `DESIGN.md`. The
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active design system decides *which* fonts; this file decides *how* they
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behave at every size.
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> Adapted from [refero_skill](https://github.com/referodesign/refero_skill)
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> (MIT) — distilled and re-tuned for OpenDesign's token system.
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## Type scale
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Use a multiplicative scale (1.2 or 1.25). Cap at 6–8 sizes per artifact.
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| Role | Range |
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|---|---|
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| Display | 48–72 px |
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| H1 | 32–48 px |
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| H2 | 24–32 px |
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| H3 | 20–24 px |
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| Body | 15–18 px |
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| Small | 13–14 px |
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| Caption | 11–12 px |
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## Line height (leading)
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| Text size | Line height |
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|---|---|
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| Display / H1 (≥32 px) | `1.0`–`1.2` (tight) |
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| Body (15–18 px) | `1.5`–`1.6` |
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| Small (≤14 px) | `1.5` |
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### CJK overrides — these are not optional
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The table above is Latin leading. Latin display type can go to `1.0`
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because the ascender/descender slack inside the em box keeps lines
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apart. **CJK glyphs fill the em box**, so the same value makes
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consecutive lines touch, and multi-line Chinese headlines visibly
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collide.
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| Text size | Latin | CJK |
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|---|---|---|
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| Display / H1 (≥32 px) | `1.0`–`1.2` | **`1.3`–`1.4`** |
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| Body (15–18 px) | `1.5`–`1.6` | `1.7`–`1.8` |
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The CJK floor has **no upper size tier**. It applies to every heading
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level, including the **cover / hero main title** — the single biggest
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headline on a deck's first slide. A Chinese cover title at 72 px,
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96 px, or larger, especially one split into multiple lines with
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`<br>`, is still CJK display text: set `line-height: 1.3`–`1.4` on
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it, never the Latin `1.0`–`1.2`. At 96 px a `1.05` leading makes the
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two lines of a Chinese cover headline visibly collide. This is the
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single most common violation, so check the cover main title first.
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Negative tracking is Latin-only for the same reason: CJK is already
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set on a fixed em grid, so `-0.02em` on a Chinese headline crowds the
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glyphs instead of tightening the word. Use `0` for CJK display text.
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When one artifact mixes both — an English kicker over a Chinese
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headline is the common case — set the tight Latin values on the Latin
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element only. Do not inherit them onto the CJK block from a shared
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parent rule.
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## Letter-spacing — the rule that makes or breaks craft
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This is the single most-skipped rule in AI-generated design. **No
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exceptions.**
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| Context | Letter-spacing |
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|---|---|
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| Body text (14–18 px) | `0` (default) |
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| Small text (11–13 px) | `0.01em` to `0.02em` (positive) |
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| UI labels and button text | `0.02em` |
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| **ALL CAPS** | **`0.06em` to `0.1em` (required)** |
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| Headings 32 px+ | `-0.01em` to `-0.02em` |
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| Display 48 px+ | `-0.02em` to `-0.03em` |
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ALL CAPS without positive tracking looks cramped and amateur. Display
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text without negative tracking looks loose and weak. These two failures
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are the most reliable AI-slop tells.
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The `0.06em` floor is not arbitrary: it is the empirical lower bound
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that print and web typographers have converged on for uppercase
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tracking (cf. Bringhurst's *Elements of Typographic Style* §3.2.7,
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which recommends 5–10% of the em for caps; modern screen practice
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rounds the lower end to 0.06em). Anything tighter and the counters
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collide on screen; the upper bound `0.1em` keeps the word from
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disintegrating into letters.
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## Font pairing
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- Maximum 2 typefaces per artifact (display + body, or one variable face
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used at multiple weights).
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- Always declare a system fallback chain. If the active `DESIGN.md`
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ships a webfont URL, the fallback must still produce a coherent look.
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- Never set `font-family: system-ui` alone on a heading — that is the
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textbook AI default; always pair it with an intentional first choice.
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## Line length
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Limit body copy to **50–75 characters** per line. In CSS:
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`max-width: 65ch` is a safe default.
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## Three-weight system
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Most well-crafted UIs use exactly 3 weights:
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- **Read** (400 / 450) — body copy
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- **Emphasize** (510 / 550) — UI text, labels, navigation
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- **Announce** (590 / 600) — headlines, buttons
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Weight 700+ is rarely needed. If your design uses bold for "emphasis on
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emphasis," it likely lacks weight discipline elsewhere.
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## Common mistakes (lint these)
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- ALL CAPS without `letter-spacing` ≥ `0.06em`.
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- Display text (≥32 px) without negative tracking (Latin only — see the CJK overrides).
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- CJK display text at Latin leading (`≤1.2`), which makes the lines overlap.
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- Multi-line CJK cover / hero titles (72–96 px+, e.g. split with `<br>`) below `1.3` line-height.
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- Negative tracking applied to CJK text.
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- More than 3 type sizes visible above the fold.
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- Mixed serif and slab on the same screen without a clear role split.
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- Body copy in `text-align: justify` (creates rivers; never use on the web).
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