Why Doesn't :not(:empty) Work for Input Fields?

Understanding the :not(:empty) CSS Selector

The :not(:empty) pseudo-class represents HTML elements that have no children. However, for void elements like , this condition is always true, regardless of whether the element has a value attributed to it.

Why :not(:empty) Does Not Work with Input Fields

Void elements, such as , do not have any child nodes. Therefore, they are always considered empty according to the HTML definition and will always match the :empty pseudo-class.

Furthermore, the Selectors specification defines :empty as an element with no children whatsoever, including child nodes like text or CDATA with non-zero length.

Consequences for CSS Styling

As a result, input:not(:empty) will never match any fields in a valid HTML document. Therefore, you cannot dynamically style empty fields based solely on CSS rules, as once text is entered, the element is no longer considered empty.

Alternative Approaches

The only way to select empty fields using CSS is to target them based on an empty value attribute (input[value=""]) or lack of value attribute altogether (input:not([value])). However, this is a static approach that does not capture changes in the input field's value after it has been populated.

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