Actually, the root certificate itself simply does not need to be checked at all, as we need to trust it anyway. In the last verification step, we verify that th

Actually, the root certificate itself simply does not need to be checked at all, as we need to trust it anyway. In the last verification step, we verify that the last intermediate certificate in the chain has a valid signature from the root CA certificate, by using the public (!) key of the root CA certificate stored in the browser.