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Turn Component State Thresholds into Ordered Container Queries

Validate named states, sort inline-size thresholds and generate component-scoped CSS.

Drop or choose a file up to 2 MB. Its contents replace the main text input; the filename alone is never treated as data.

Reviewable output

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Processed

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Warnings / conflicts

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Output state

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How the calculation works

Local inputboundedPer-item ruledeterministicArtifactcopy / download

How to Use This Tool

Validate named states, sort inline-size thresholds and generate component-scoped CSS. Generate ordered CSS container queries from component state thresholds, detect duplicate breakpoints, and export a deterministic responsive scaffold.

The work this page finishes

Viewport breakpoints do not describe a reusable card placed in different parents, while unsorted or duplicate container thresholds create ambiguous component states. For Container Query Builder, the row-preserving workspace makes a correction repeatable without rebuilding a prompt or transmitting the source file.

Rows or choicesValidate every itemReview and export
The default card scaffold creates compact, comfortable and wide states at 0, 420 and 720 pixels in deterministic order.

Deterministic workflow

Require safe CSS identifiers, unique integer inline-size thresholds and ascending order, then emit one named size container and one min-width query per state. For Container Query Builder, this page accepts at most 5,000 records and 2 MB of text; rejected items retain their row references while valid items remain available.

Why a dedicated interface helps

Replace the custom-property placeholder with real component declarations and test widths immediately before and after every boundary. For Container Query Builder, immediate recalculation and a stable export are useful when the same rule must be applied consistently across a list instead of explained one item at a time.

Assumptions

  • Thresholds refer to container inline size.
  • State names are CSS-safe identifiers.
  • The component has a suitable containment ancestor.

For Container Query Builder, retain the original source until the destination accepts the result; processing stays in this tab, although the device and installed extensions remain part of the user's security boundary.

Limitations and review boundary

It does not infer good breakpoints, parse arbitrary selectors, generate style queries, polyfill unsupported browsers or prove that a component is visually usable. For Container Query Builder, no supplied URL is requested and no pasted markup or code is executed; output is inserted through text-only DOM operations.

Verification and provenance

The implementation was checked against W3C CSS Containment Module Level 3 on 2026-08-26, with fixtures for a known answer, an invalid input and a batch-specific edge condition. The default card scaffold creates compact, comfortable and wide states at 0, 420 and 720 pixels in deterministic order.

Sources & assumptions

Tool Spec v2 · verified 2026-08-26. Platform rules and fees can change; the editable inputs remain authoritative for your account.

Official references

Model assumptions

  • Thresholds refer to container inline size.
  • State names are CSS-safe identifiers.
  • The component has a suitable containment ancestor.
  • It does not infer good breakpoints, parse arbitrary selectors, generate style queries, polyfill unsupported browsers or prove that a component is visually usable.
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Frequently Asked Questions

What does Container Query Builder complete?
It applies the stated generator rule to container query builder inputs and produces the reviewable output shown above.
Why use a dedicated Container Query Builder page instead of chat?
The Container Query Builder workflow preserves ordering, applies identical validation on every run and creates an artifact without conversational drift.
Does Container Query Builder send the input to ecech?
No. Container Query Builder reads pasted or selected content inside the current browser tab and does not call an ecech calculation API.
What verifies the default result?
The default card scaffold creates compact, comfortable and wide states at 0, 420 and 720 pixels in deterministic order.
When should I reject the output?
It does not infer good breakpoints, parse arbitrary selectors, generate style queries, polyfill unsupported browsers or prove that a component is visually usable.
Which reference supports Container Query Builder?
The recorded Container Query Builder reference is W3C CSS Containment Module Level 3, reviewed 2026-08-26.

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