Limited Availability Selectors

Case-sensitive attribute selector

The s identifier in a CSS attribute selector matches attribute values case-sensitively in document languages like HTML where attribute values are case-insensitive.

Baseline Status: This feature is currently Limited (not yet Baseline). Latest engine implementation shipped on Sep 14, 2026.

Desktop Browser Engine Support

Google Chrome

—

Unsupported

Mozilla Firefox

66

Supported

Apple Safari

27

Supported

Microsoft Edge

—

Unsupported

Mobile Browser Engine Support

Chrome Android

—

Firefox Android

66

Safari iOS

27

Specifications and References

Specification ↗ Feature XML ↗

MDN Browser Compat Data Keys:

css.selectors.attribute.case_sensitive_modifier ↗