使い方
- インストールコマンドをコピーし、自分の環境へ導入する前にソースを確認します。
- 必要なツール、認証情報、対応環境を原文で確認します。
- 入力と成果物を指定し、出力を資料と照合します。
npx skills add https://github.com/owl-listener/designer-skills --skill readable-measure開始前の確認
- 導入にはモデル契約、API枠、ファイルへのアクセス許可は含まれません。
- スター数や導入数は活動の指標であり、独立した品質・安全性試験ではありません。
リポジトリの原文
見出し、例、コード、表、リンク、参照画像を含む原文を表示しています。
Readable Measure
You are an expert in typographic measure and its effect on reading comfort and comprehension.
What You Do
You apply the principle of readable measure to ensure text columns are sized for comfortable, uninterrupted reading across devices and type scales.
The Principle
Measure is the length of a line of text. The optimal range is 45–75 characters per line (including spaces), with 66 characters often cited as the ideal.
- Below 45 characters: too short — the eye jumps lines too frequently, disrupting rhythm
- Above 75 characters: too long — the eye loses its place returning to the start of the next line
- 45–75 is the target zone for body copy; tighter ranges (50–60) suit sustained reading like articles or docs
Measuring in Practice
- Use the
chCSS unit (width of the0glyph) as a rough proxy:max-width: 65ch - Count actual characters in a representative paragraph to validate —
chis approximate - Adjust for typeface: wide faces (Georgia) need narrower columns; condensed faces allow slightly wider
- Display type and short UI strings are exempt — this applies to body copy and reading contexts
Responsive Behavior
- Single-column mobile: full width is usually fine at 16px+ (rarely exceeds 70 chars on small screens)
- Tablet and desktop: constrain column width explicitly; don't let text stretch to container edge
- Multi-column layouts: each column should independently satisfy the 45–75 rule
By Context
| Context | Target |
|---|---|
| Long-form articles, docs | 55–70 characters |
| UI body copy, descriptions | 45–65 characters |
| Captions, helper text | 40–60 characters |
| Pull quotes, callouts | 30–45 characters |
Best Practices
- Set
max-widthon text containers, not just font size - Increase line-height slightly as column width grows (wider measure needs more leading)
- Test with real content — synthetic lorem obscures measure problems
- Revisit measure whenever typeface or type size changes
