https://b.hatena.ne.jp/entry/s/developer.mozilla.org/en-US/docs/Web/CSS/Reference/Selectors/:user-invalid This feature is well established and works across many devices and browser versions. It’s been available across browsers since November 2023. Learn more See full compatibility The :user-invalid CSS... https://b.hatena.ne.jp/yug1224/20250326#bookmark-4768034438117810465 2025-03-26T02:53:08Z https://b.hatena.ne.jp/efcl/20250324#bookmark-4768034438117810465 blurしたときにformのinvalidを表現する`:user-invalid` 2025-03-24T14:53:45Z HTML css