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
5-
1
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.
-
2
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.
-
3
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.
-
4
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.
-
5
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
Z-Index Registry
Z-Index Registry
Keep every stacking value in one file so nobody has to guess a bigger number.
What it does
A single source of named z-index tokens, with reserved ranges per layer and a check that blocks raw values.
How it works
- 1 Find every z-index in the codebase, including inline styles and values buried in third-party overrides, and list them with the component that owns each. The count is usually higher than anyone expects and several will be arbitrary large numbers.
- 2 Reserve a range for each layer rather than assigning single values, so a new dropdown can slot between existing ones without renumbering everything above it. Leave real gaps between ranges.
- 3 Name each token after the layer it belongs to and derive the ordering from Elevation Layer Map. That feature decides what covers what; this one holds the numbers and stops them being invented locally.
Copy the prompt
No account needed
Add this feature to my app:
https://addthisfeature.com/x/z-index-registry
Spacing Scale
Spacing Scale
Reduce the app's spacing to a small set of steps that repeat across every surface.
What it does
A named spacing scale covering gaps, padding, and section rhythm, with every existing value in the app mapped onto it.
How it works
- 1 Collect every spacing value currently in the codebase and count how often each appears. The result is usually a handful of genuine intentions surrounded by dozens of near-misses that were nudged once and never revisited.
- 2 Define a scale that is fine at the small end, where control padding lives, and coarse at the large end, where section separation lives. A linear scale gives too many indistinguishable large steps and too few small ones.
- 3 Separate the tokens used inside a component from the ones used between components and between page sections, and name them so the difference is obvious. The same number serving both purposes means a change to button padding also changes the gap between sections.
Copy the prompt
No account needed
Add this feature to my app:
https://addthisfeature.com/x/spacing-scale
Shadow Scale
Shadow Scale
Replace ad hoc shadows with a small set tied to what each surface actually is.
What it does
A fixed ladder of shadow tokens, each named for an elevation role rather than a blur radius.
How it works
- 1 Collect every shadow currently declared anywhere in the app and group them by what they sit on — a resting card, a hovered card, a dropdown, a dialog, a toast. Most apps have a dozen near-identical values that collapse into four or five roles.
- 2 Name each step for its role, not its appearance. A token called menu tells the next person which surfaces may use it; a token called shadow-md-2 does not.
- 3 Use a single light source for the whole scale, so offset, blur, and spread grow together as elevation rises. Two shadows lit from different directions on the same screen read as a rendering bug.
Copy the prompt
No account needed
Add this feature to my app:
https://addthisfeature.com/x/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.