Back to Error DirectoryW3C EPUBCheck Standard
CSS-006Retailer Warning

CSS selector specifies fixed position.

CSS selector specifies fixed position.

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What This Error Means in Plain English

EPUBCheck detected CSS selector specifies fixed position.. Digital reading systems and bookstores require standard conformance to ensure compatibility across all reading apps.

Why Retailers & EAA Regulations Block This File

Automated book distributors (Apple Books, Amazon KDP, Kobo, and IngramSpark) run strict EPUBCheck validation on ingest and reject non-compliant files.

Technical Specification: W3C EPUBCheck rule CSS-006: CSS selector specifies fixed position.

Manual Fix Instructions (for Sigil / Calibre)

  1. Locate the file and line flagged under rule CSS-006 in your EPUB editor (Sigil or Calibre).
  2. Apply the required syntax correction matching the CSS-006 specification.
  3. Re-pack and validate with PreFlight EPUB to confirm zero residual errors.