Container Width System
Give pages a few defined widths instead of a different max-width on every screen.
What it adds
A small set of named page widths — narrow, standard, wide, and full-bleed — applied consistently across the app.
What your agent is told to do
5
What your agent is told to do
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Measure the max-width used on every top-level page and group them. Settings forms, prose, dashboards, and data tables usually want three or four distinct widths between them, not the eleven the codebase currently has.
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Pick each width from the content it holds. A reading column is bounded by comfortable line length, a settings form by field width, and a table by the number of columns that must stay visible.
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Make horizontal page padding part of the container rather than something each page adds, so content never touches the viewport edge on a narrow screen even at the widest setting.
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Give full-bleed sections a defined way to escape the container and return, so a hero band or a full-width table can span the viewport while the text above and below stays aligned to the same column.
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Do not force data-heavy screens into the reading width. Wide tables, canvases, and dashboards need the viewport, and constraining them to a prose column trades a real workflow for a typographic preference.
Edge cases it handles
7
Edge cases it handles
7- Horizontal padding must survive at every width. A container that only sets max-width will let text run into the screen edge on small viewports, where the constraint is padding rather than the maximum.
- Some sections legitimately need to break out — full-bleed images, sticky table headers, edge-to-edge banners — so there must be a supported escape rather than each page reaching for negative margins.
- Modals, drawers, and side panels need widths drawn from the same set, or a dialog containing the same form as a page will render it at a different measure and look like a different product.
- Article and documentation screens should stay narrow while data screens go wide, and a single global maximum cannot serve both, so the width belongs to the page rather than to the layout shell.
- Nested containers silently compound their padding, so a container placed inside another must detect that and contribute nothing rather than doubling the inset.
- Breakpoint values used to switch between widths come from Breakpoint Token System, and column counts and gutters inside a container come from Responsive Grid Tokens; this feature owns the outer boundary only.
- A width expressed only in pixels will not respond to the user's root font size, which matters on screens that are mostly text.
Definition of done
9
Definition of done
9- The app defines no more than five named page widths and every page uses one of them.
- No page declares its own max-width outside the system.
- Content keeps its horizontal padding at every viewport size and never touches the screen edge.
- There is a supported full-bleed escape that returns to the same alignment afterwards.
- Modals, drawers, and panels draw their widths from the same set as pages.
- Data-heavy screens are not constrained to the reading width.
- Nested containers do not double their padding.
- The feature matches the existing design system.
- No existing functionality is broken.
Related features
Semantic Color Tokens
Semantic Color Tokens
Name colours by the job they do, so changing a theme is one edit rather than a sweep.
What it does
A vocabulary of role-named colour tokens — surface, text, border, accent, danger, success — that components reference instead of literal values.
How it works
- 1 Inventory every literal colour value in the codebase and group them by the job they are doing rather than by the shade they happen to be. Two different greys used as card backgrounds are one role; the same grey used as a background and as a border is two.
- 2 Define the role names once and map each role to a value per theme. A role may resolve to a light grey in one theme and a near-black in another; what must not change is which components reference it.
- 3 Stop shared components accepting raw colour values. A primitive that takes a hex string as a prop guarantees that some product screen will hardcode a colour the themes never learn about.
Copy the prompt
No account needed
Add this feature to my app:
https://addthisfeature.com/x/semantic-color-tokens
Text Measure Guardrails
Text Measure Guardrails
Hold long-form text to a readable line length instead of letting it run the full width.
What it does
A maximum measure applied to the app's prose containers, with named exceptions for content that needs the whole width.
How it works
- 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.
Copy the prompt
No account needed
Add this feature to my app:
https://addthisfeature.com/x/text-measure-guardrails
Motion Token System
Motion Token System
Give the app one shared vocabulary of durations and easing curves instead of ad hoc numbers.
What it does
A named set of durations and easing curves, each tied to a category of motion, replacing the timing values scattered through the app's components.
How it works
- 1 Inventory every duration and easing value currently written into the app and group them by what they do: something entering, something leaving, something being emphasised, and something changing size or position.
- 2 Name a small set of durations — roughly instant, quick, standard, and deliberate — and a small set of curves, then map each motion category to a pairing. Four or five of each is enough for an entire product.
- 3 Give entrances and exits different treatment. Something arriving should decelerate into place; something leaving should accelerate away and take less time, because nobody wants to wait for a dismissal.
Copy the prompt
No account needed
Add this feature to my app:
https://addthisfeature.com/x/motion-token-system
How it works
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1
Copy the link
Grab the Markdown instruction URL for this feature.
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Give it to your AI
Paste it into Claude Code, Cursor, v0, Lovable — whatever you build with.
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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.