CSS Custom Property Bridge
Expose the design tokens as CSS variables so theming and styling can change at runtime.
What it adds
A generated layer of CSS custom properties mirroring the token source, which components are expected to style against.
What your agent is told to do
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What your agent is told to do
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Generate the custom properties from the same token source the rest of the app already uses, so a token and its variable can never disagree. A hand-maintained parallel list will drift within a release.
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Decide and document where each group of variables is declared — the document root for global theme values, a container for anything that must vary per section or per component — and apply that rule consistently.
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Fix the naming scheme and treat the generated names as a public contract, since stylesheets, components, and any customer-facing theming all reference them by name.
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Give every consumption point a fallback value so a component still renders sensibly when a variable is absent, which is the normal state during theme switching and partial loads.
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Coordinate with Unused Token Detection: that feature judges whether a token is still referenced, and it must be able to see references made through these variables, or every bridged token will look dead.
Edge cases it handles
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Edge cases it handles
7- A theme that defines only some of the variables must not leave components unstyled. Every reference needs a fallback, and the base theme must supply a complete set beneath any partial one.
- Scope decides behaviour: a variable declared at the document root affects everything, one declared on a container affects only its subtree. A value intended to vary per section but declared globally will leak into every other section on the page.
- Generated names must stay stable across builds. A name that changes because a build step reordered or hashed it will break every stylesheet and every customer theme that referenced it.
- Custom properties are readable by anything running on the page, so nothing derived from configuration, keys, entitlements, or internal identifiers may be emitted into them. Only presentation values belong here.
- Values that participate in animation or transition must be declared with a type, or the browser will step between them rather than interpolating.
- Switching themes must not repaint through an intermediate state where some variables have updated and others have not.
- A variable referencing another variable that is itself undefined resolves to nothing rather than to the fallback the author expected, so chains need a fallback at each step.
Definition of done
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Definition of done
9- Every custom property is generated from the token source, with no hand-maintained duplicates.
- The scope of each variable group is documented and matches where it is declared.
- Generated names are stable across builds and treated as a public contract.
- Every consumption point carries a fallback and renders sensibly under a partial theme.
- No configuration, credential, or internal identifier is exposed as a custom property.
- Theme switching applies in one pass with no visible intermediate state.
- Unused Token Detection resolves references made through the bridge.
- 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
Tokenized Inline Styles
Tokenized Inline Styles
Allow styles computed at runtime without letting arbitrary values escape the design system.
What it does
A constrained path for dynamically computed styles, where every value is either a design token or a number clamped to an approved range.
How it works
- 1 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.
- 2 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.
- 3 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.
Copy the prompt
No account needed
Add this feature to my app:
https://addthisfeature.com/x/tokenized-inline-styles
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
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.