CSS Conformance
Lanexio™ Parser implements the CSS Syntax Module Level 3 tokenizer and parser. The conformance suite validates tokenization, selector parsing, at-rule recognition, and value extraction against the W3C test corpus.
Test results
Section titled “Test results”991 tests pass, 2 skipped. The two skipped tests require runtime layout information not available in a headless parser.
The CSS grammar includes parseCss for single stylesheet parsing, extractCSS for embedded <style> content, and parseAllCSS for multi-stylesheet documents. A validateValues utility checks CSS property values against known syntax rules.
Four-axis bar
Section titled “Four-axis bar”| Axis | Result |
|---|---|
| never-throw | 0 throws |
| well-formed | gated, corpus clean |
| lossless | skipped (CSS normalizes source) |
| conformance | 991/991 passing, 2 skipped |
CSS normalizes whitespace and formatting during parsing, so byte-exact lossless round-trip does not apply. The conformance gate verifies structural correctness of the parse tree.
Corpus conformance
Section titled “Corpus conformance”pnpm conformance:suite measured this family over the test_files/css corpus on 2026-10-06 at
Lanexio™ Parser version 1.0.0:
| family | valid | invalid | raw | contract-subset | REAL-DEFECT |
|---|---|---|---|---|---|
| css | 353 | 0 | 100.0% | 100.0% (353/353) | 0 |