Unknown pseudo-element or pseudo-class :focus-within

i am getting this error in w3 validations is there any way to solve it i tried many ways but not able to resolve it.

Ignore it but be aware :focus-within doesn’t work on Microsoft browsers?

i want to escape with the error or i need any alternative that works the same.

Your two options are 1. ignore the validator or 2. don’t use :focus-within if it’s really important to you to use the W3 validator. The validator validates that something is completely compliant: :focus-within cannot be completely compliant because it just flat out doesn’t work in some browsers (IE, all current version of Edge and MS mobile browsers). The validator will tell you what doesn’t fit into its strict criteria of valid, that’s all.