Do HTML Class Names Matter in CSS Selectors: Case Sensitivity Explained?

Are HTML Class Names Case-Sensitive in CSS Selectors?

CSS selectors are generally not case-sensitive, meaning that class and ID selectors can match elements regardless of the case of their names. However, HTML class names themselves are case-sensitive, leading to the discrepancy in the example provided.

In the given selector .holiday-type.Selfcatering, the use of a capitalized letter "S" in the class name "Selfcatering" results in a mismatch with the HTML element's class name of "Selfcatering," which is lowercase. Therefore, the style is not applied.

This behavior is due to the case-sensitivity of HTML class names, as defined by its attribute definition. Despite the case-insensitivity of CSS selectors, the mismatch in case between the selector and the HTML element prevents the selector from matching.

It's important to note that the case-sensitivity of selectors is influenced by the document language. In the case of HTML, element names, attribute names, and attribute values in selectors are case-sensitive. This means that while selectors like .Selfcatering and [class~="Selfcatering"] will match the HTML element with the "Selfcatering" class, .SelfCatering and [class~="SelfCatering"] will not.

If the document type defined class names as case-insensitive, the selectors would match regardless of case. However, in HTML, class names retain their case-sensitivity, ensuring consistency with the document language.

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