#449 · Developer Tool

CSS Custom Property Extractor

Extract CSS custom property declarations and `var()` references into a reusable inventory. The report preserves selector context, values, source lines, fallbacks, duplicate definitions, and references that have no declaration in the pasted stylesheet. It is aimed at token audits, theme reviews, and small migration tasks where a full CSS build pipeline would be unnecessary.

Developer Input

CSS variable inventory
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How to use this developer tool

  1. Paste source text or load the representative sample.
  2. Adjust the available parsing option when the tool provides one.
  3. Select Extract Properties or press Ctrl/Cmd + Enter.
  4. Review the summary, issues, and copy-ready output before using it.

What this developer tool does

Comments are removed while line breaks are preserved. Rule blocks are scanned for `--name: value` declarations, and the full stylesheet is scanned for `var(--name, fallback)` references. Definitions are grouped by property name.

Comments are removed while line breaks are preserved. Rule blocks are scanned for `--name: value` declarations, and the full stylesheet is scanned for `var(--name, fallback)` references. Definitions are grouped by property name.

The extractor handles ordinary CSS rule blocks. Deeply nested preprocessor syntax or values containing unmatched braces may require a dedicated parser.

Example

Input

 :root {
  --color-brand: #7c3aed;
  --space-card: 1.25rem;
}
[data-theme="dark"] {
  --color-brand: #a78bfa;
  --surface: rgb(15 23 42);
}
.card { padding: var(--space-card); color: var(--color-brand, purple); }

Expected result

Run the sample to see a structured report generated by the same processing logic used for pasted input.

Use cases

  • Review front-end source during a code migration.
  • Create a structured handoff for documentation or QA.
  • Catch input-specific issues before committing generated output.

Tips for reliable output

  • Paste the smallest complete fragment that reproduces the case.
  • Use the sample once to confirm the expected input shape.
  • Review warnings instead of treating a clean report as a guarantee.
  • Keep the original source in version control before replacing it.
  • Test generated output in the target browser or application.

Processing details

Comments are removed while line breaks are preserved. Rule blocks are scanned for `--name: value` declarations, and the full stylesheet is scanned for `var(--name, fallback)` references. Definitions are grouped by property name.

The extractor handles ordinary CSS rule blocks. Deeply nested preprocessor syntax or values containing unmatched braces may require a dedicated parser.

Frequently asked questions

Are fallback values from var() references extracted?

Yes. A fallback after the first comma is included in each reference record.

How are theme-specific variable definitions represented?

Each definition keeps the selector of its rule, so the same property can appear under :root and theme selectors.

What is an unresolved custom property reference?

It is a var(--name) reference with no matching declaration anywhere in the pasted CSS.

Are CSS comments included in extracted values?

Comments are removed while line breaks are preserved for approximate source-line reporting.

Can this parse nested Sass or Less syntax?

Not reliably. The extractor targets ordinary flat CSS rule blocks, not preprocessor grammars.

Output fields

FieldMeaning
SummaryCount and outcome of the current run
InterpretationWarnings and practical review guidance
ExportsCopy-ready output plus CSV or JSON when available

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