Text Measure Guardrails

Hold long-form text to a readable line length instead of letting it run the full width.

simple Design Systems

What it adds

A maximum measure applied to the app's prose containers, with named exceptions for content that needs the whole width.

What your agent is told to do

1
Find every surface that renders more than a couple of sentences — help articles, changelog entries, terms pages, long empty-state explanations, in-app announcements — and cap the measure on the text container itself rather than on the page shell.
2
Express the cap in units that scale with the type, so a larger heading or a user who has raised their base font size gets a proportionally wider column instead of a cramped four-word line.
3
Declare which elements are allowed to break out of the measured column — tables, code blocks, images, video, diagrams, full-bleed callouts — and let them span the container while the paragraphs around them stay narrow.
4
Do not centre long-form copy to make the narrow column look deliberate. A ragged left edge makes the eye hunt for the start of every line, which is the cost the measure was meant to remove.
5
Keep this entry to width only. Text Wrapping Rules owns what happens inside a line — where it breaks, when it truncates, how it hyphenates — so the two briefs do not both try to define overflow behaviour.

Edge cases it handles

Tables, code samples, and media that are forced into the prose measure become unreadable or scroll horizontally. Let them break out to the container width while the surrounding paragraphs stay capped.
A measure tuned for body text is too narrow for large display type and too wide for small print. Adjust the cap per step of the type scale rather than applying one number to everything.
Centred long-form paragraphs cost the reader a fixation on every line return. Reserve centring for single lines such as a page title or an empty-state message.
The cap must be a maximum, not a fixed width. On a narrow viewport the column has to shrink and keep its gutters, or the text runs into the screen edge.
Nested containers that each apply the cap compound it and produce a column half the intended width. Apply the measure once, at the outermost prose wrapper.
In right-to-left locales the column must align to the right edge, not stay pinned left.
A user who zooms the browser or enlarges their default font must get fewer characters per line, not a horizontally scrolling page.

Definition of done

Every long-form surface renders its paragraphs within a bounded measure rather than the full page width.
The measure scales with the type size instead of being a single fixed value across the app.
Tables, code blocks, and media render at the container width while adjacent paragraphs stay measured.
No long-form body copy is centred.
On narrow viewports the column shrinks and retains its gutters, with no horizontal scrolling.
Nesting two prose containers does not halve the column width.
The feature matches the existing design system.
No existing functionality is broken.

Related features

Z-Index Registry

Spacing Scale

Shadow Scale

How it works

1

Copy the link

Grab the Markdown instruction URL for this feature.
2

Give it to your AI

Paste it into Claude Code, Cursor, v0, Lovable — whatever you build with.
3

It inspects, then implements

Your agent reads your existing app first, then adds the feature to fit it.

Works with your stack

These instructions are written to adapt. They tell the agent to detect your framework, match your existing design system, and reuse what you already have — rather than assuming a particular stack.

Need it tighter than that? Customize the feature and tell it exactly what you're running.