Breakpoint Token System
Name the app's breakpoints once so the same numbers stop appearing everywhere.
What it adds
A shared set of named breakpoints, available to both stylesheets and runtime code from a single definition.
What your agent is told to do
5
What your agent is told to do
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Collect every media query threshold in the codebase and count the distinct values. Anything within a few pixels of a neighbour is the same breakpoint written twice and should be merged before tokens are named.
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Name each breakpoint for the layout change it causes — the point where the sidebar collapses, where the table becomes cards — rather than for a device. Device names date badly and stop describing anything once screen sizes move.
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Derive the runtime values from the same definition the stylesheets use, so code that decides whether to render a drawer or a dialog agrees with the CSS about which one is on screen.
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Keep the set small. Four or five thresholds cover almost every layout, and each additional one multiplies the states that have to be designed, built, and checked.
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Do not reach for a breakpoint when the question is about the component's own container. Viewport breakpoints belong here; a component that must adapt to the space it is given should use a container query, and Responsive Grid Tokens covers the grid case.
Edge cases it handles
7
Edge cases it handles
7- CSS and runtime values drifting apart is the classic failure — the stylesheet switches to a mobile layout while the code still believes it is on desktop, and the user gets a desktop drawer inside a mobile shell. One definition must feed both.
- Names taken from devices mislead the next reader, because a tablet in landscape is wider than several laptops and nobody can tell from the name which layout the token actually triggers.
- Every added breakpoint doubles the combinations to verify, so a set that grows past five or six becomes untestable and layouts start breaking in the ranges nobody checked.
- Container queries and viewport breakpoints must have separate territories, or a component will respond twice to a change in width and produce an intermediate layout that was never designed.
- Mixing minimum-width and maximum-width queries in the same system leaves a one-pixel gap or a one-pixel overlap at each threshold, where either both rules apply or neither does.
- Breakpoints expressed in pixels ignore the user's root font size, so a page zoomed for legibility will not switch layout when it should.
- Runtime breakpoint checks must re-evaluate on resize and orientation change, not only on first render, or a rotated device keeps the layout it started with.
Definition of done
9
Definition of done
9- All breakpoints come from one definition consumed by both stylesheets and runtime code.
- There are no more than six named breakpoints and none are named after devices.
- No raw pixel threshold appears in a media query outside the token set.
- Runtime layout decisions and CSS layout always agree about the current breakpoint.
- Thresholds do not overlap or leave a gap at their boundaries.
- Container-driven adaptation uses container queries rather than viewport breakpoints.
- Layout responds correctly to browser zoom and to orientation change.
- 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
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
Container Width System
Container Width System
Give pages a few defined widths instead of a different max-width on every screen.
What it does
A small set of named page widths — narrow, standard, wide, and full-bleed — applied consistently across the app.
How it works
- 1 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.
- 2 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.
- 3 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.
Copy the prompt
No account needed
Add this feature to my app:
https://addthisfeature.com/x/container-width-system
How it works
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1
Copy the link
Grab the Markdown instruction URL for this feature.
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2
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.