sibling-count() and sibling-index()

The sibling-count() and sibling-index() CSS functions return integers that are useful to style elements based on their positions among siblings or on the number of siblings, for example as part of a calc() expression.

Baseline Status: Achieved Newly Available on Aug 18, 2026 across core engines.

Desktop Browser Engine Support

Google Chrome

138

Supported

Mozilla Firefox

154

Supported

Apple Safari

26.2

Supported

Microsoft Edge

138

Supported

Mobile Browser Engine Support

Chrome Android

138

Firefox Android

154

Safari iOS

26.2

Specifications and References

Specification ↗ Feature XML ↗

MDN Browser Compat Data Keys:

css.types.sibling-count ↗ css.types.sibling-index ↗