Border System
Give borders defined jobs so structure, focus, and selection never look the same.
What it adds
A set of border tokens covering structural dividers, interactive outlines, focus rings, selection, and error emphasis.
What your agent is told to do
5
What your agent is told to do
5-
1
Audit every border in the app and sort it into one of a few jobs: separating content, outlining a control, marking focus, marking selection, or signalling an error. Anything that does not fit a job is decoration that should be removed rather than tokenised.
-
2
Keep structural borders and interactive borders visually distinct. A divider between table rows and the outline of a text input should not share a colour, or users will read inert content as clickable.
-
3
Define focus separately from selection and from hover. Focus follows the keyboard, selection follows intent, and a control that is both focused and selected must show both without one hiding the other.
-
4
Give the dark theme its own border values. A border that reads as a subtle grey on white becomes invisible on a near-black surface, and raising its opacity is not the same as picking the right colour.
-
5
Do not use a border token to imply elevation or stacking order. Boundaries are this feature's job, elevation belongs to Shadow Scale, and paint order belongs to Elevation Layer Map.
Edge cases it handles
7
Edge cases it handles
7- Decorative dividers and interactive outlines must remain separable at a glance, otherwise a non-clickable panel edge is mistaken for a control and a real control loses its affordance.
- Subtle borders that work on a light background disappear on dark surfaces, so each token needs a dark-theme value chosen against the actual surface it will sit on, not derived by inverting the light one.
- Nesting a bordered component inside a bordered container produces a doubled two-pixel line at the shared edge. Decide which layer owns the boundary and have the inner element drop its border or collapse into the outer one.
- Hairline borders at high device pixel ratios round unpredictably and can render at zero width on some rows and full width on others, producing a striped table. Use a technique that survives fractional scaling rather than a fixed sub-pixel value.
- Focus rings must not be clipped by an ancestor that hides overflow, and must retain contrast against both the component and the page behind it.
- A border used to signal an error must not be the only signal, because colour alone fails for users who cannot distinguish it and for forced-colours mode.
- Rounded corners share the border radius scale, so a token change that alters width without accounting for radius will leave visible gaps at the corners of nested elements.
Definition of done
8
Definition of done
8- Every border in the app resolves to a token with a named job.
- Structural, interactive, focus, selection, and error borders are visually distinct from one another.
- Each token has a dark-theme value verified against the surface it appears on.
- No nested component renders a doubled border at a shared edge.
- Hairline borders render at consistent width across device pixel ratios.
- Focus rings are visible on every interactive element and are never clipped by an ancestor.
- 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.