-webkit-box-flex-group - This property has virtually zero usage based on the UseCounter on stable. % values of -webkit-line-clamp - There is interest in finding a standards based solution to the number values usecase, but we haven’t seen demand for the %-based values. -webkit-box-lines - This property was never fully implemented. It was originally intended such that a “vertical”/”horizontal” -webkit-box can have multiple rows/columns.