W3C validator does not support nested CSS (2026-07)

By Xah Lee. Date: 2026-07-11. Last updated: 2026-09-10.

2026-07-11

The w3c validator does not support nested css

amazing. the w3c css validator still no do nested css syntax.

2026-09-10

now the W3C validator support nested CSS. finally. just a few months ago, in 2026-06-10, it doesn't.