Tokenized Inline Styles
Allow styles computed at runtime without letting arbitrary values escape the design system.
What it adds
A constrained path for dynamically computed styles, where every value is either a design token or a number clamped to an approved range.
What your agent is told to do
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What your agent is told to do
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Find every place the app already sets a style value at runtime — progress widths, chart bar heights, avatar colours, drag positions, user-chosen accent colours — and sort them into two groups: values that must come from the token set, and values that are genuinely continuous numbers.
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For the first group, accept only token names and resolve them to values at the boundary. A caller passing a raw colour or a raw pixel value should be rejected loudly in development rather than quietly rendered.
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For the second group, clamp to a documented minimum and maximum and round to a sensible precision, so a percentage of 4000 or a width of 0.3847291 pixels never reaches the DOM.
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Treat any value that originated with a user or another tenant as untrusted. Strip anything that could terminate a declaration or introduce a new one, and never let a user-supplied string reach a URL-valued property.
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Do not solve this by generating a new class per distinct value. A stylesheet that grows with your data is a memory and parse cost that shows up only at scale, and it defeats the caching the app already relies on.
Edge cases it handles
7
Edge cases it handles
7- A caller that passes an arbitrary hex colour or a hand-written pixel value where a token is required must be rejected, not silently accepted — otherwise the token set stops describing the app within a release or two.
- Values that originated with a user or an external system must be sanitised before they are used, because a style value is a place markup can be smuggled in and a place a remote request can be triggered.
- Server-rendered and client-rendered output must agree exactly on the first paint. A value rounded differently on the two sides produces a hydration mismatch and a visible flash.
- The number of distinct generated rules must stay bounded. Styling a thousand rows with a thousand unique declarations is a cost that only appears on the largest accounts.
- A token that is removed or renamed later must fail visibly at the point of use rather than resolving to an empty value and rendering an unstyled element.
- Theme changes must flow through the same path. A runtime style that hardcodes a resolved colour will not follow the user into dark mode.
- Animated values updated every frame must not go through the token resolver on each tick; resolve once and interpolate.
Definition of done
8
Definition of done
8- Every runtime style value is either a named token or a number clamped to a documented range.
- Passing an off-system value where a token is required fails visibly in development.
- User-supplied and third-party values are sanitised before they reach any style property.
- Server and client render identical style output on first paint, with no hydration mismatch.
- The count of distinct generated style rules does not grow with the number of records displayed.
- Runtime-styled elements follow theme changes without being re-mounted.
- The feature matches the existing design system.
- No existing functionality is broken.
Related features
Variant Class Generator
Variant Class Generator
Declare a component's variants once instead of scattering conditionals through its markup.
What it does
A declarative variant definition per component mapping size, tone, and state to the classes each combination produces.
How it works
- 1 Find the components whose markup is threaded with conditional class logic and replace that logic with a single declaration listing each variant, its options, and its default.
- 2 Support combinations that are more than the sum of their parts, so a specific pairing of size and tone can produce classes that neither produces alone, without reintroducing a conditional in the markup.
- 3 Make invalid combinations impossible to express rather than merely undesirable, and give the component a defined appearance when it receives a combination it does not recognise.
Copy the prompt
No account needed
Add this feature to my app:
https://addthisfeature.com/x/variant-class-generator
Class Merge Helper
Class Merge Helper
Combine conditional classes in one place so the last one written actually wins.
What it does
A single helper every component uses to resolve base, conditional, and caller-supplied classes into one final list.
How it works
- 1 Find every component that currently builds a class string by hand and route all of them through one helper, so the resolution rules are identical everywhere.
- 2 Define the precedence plainly: the component's own base classes lose to its variant classes, and both lose to whatever the caller passed in. A caller that supplies a class expects it to take effect.
- 3 Accept the shapes calling code actually produces rather than forcing every call site to normalise first, and make the behaviour for absent and empty values explicit rather than incidental.
Copy the prompt
No account needed
Add this feature to my app:
https://addthisfeature.com/x/class-merge-helper
CSS Module Boundaries
CSS Module Boundaries
Keep each component's styles its own, and make the shared parts deliberate.
What it does
A boundary around each component's styles, exposing only a named set of hooks that callers are permitted to style through.
How it works
- 1 Identify the primitives the rest of the app builds on — button, field, card, menu, table — and treat everything inside them as private unless it is deliberately published.
- 2 For each primitive, publish an explicit surface: the variants it accepts, the slots a caller may target, and the custom properties it reads. Anything not on that list is internal and may change without notice.
- 3 Find the places where product screens currently reach into a primitive's internals and rewrite them to use the published surface, adding a variant or a slot where the need is legitimate.
Copy the prompt
No account needed
Add this feature to my app:
https://addthisfeature.com/x/css-module-boundaries
How it works
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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.