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14026 :: A CSS parser + full MDN grammar validator, written in Nimony

• timbuktu (orginal) [2026-07-04T17:08:56+02:00] view original

  css parses a whole stylesheet and validates every value against its MDN grammar, every function against its own signature, and every selector against Selectors-4.

  Stdlib only, no deps.

  import css
  
  validateValue("width", "clamp(1rem, 2vw, 3rem)").valid  # true
  validateValue("width", "clamp(1rem, 2vw)").error  # "clamp() expects 3 arguments, got 2"
  validateValue("color", "rgb(1, 2)").error  # "invalid arguments to rgb(): ..."
  Run

  It validates the entire Bootstrap stylesheet (5,542 declarations, 2,556 selectors) with zero false positives — faster per declaration than css-tree, the only other tool I found that grammar-checks values at all. And nothing else does the recursive clamp(calc(...), min(...), max(...)) math grammar, arity and all.

  Compiled with nimony, AOT, no JIT — the parser keeps pace with Rust lightningcss.

  https://github.com/aoughwl/css

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