Are you redirecting your app to your Org’s sign in widget, or are you self hosting the same with your Angular app? If it’s the first, are you using your org’s custom domain or the base *.okta.com domain?
If you are embedding, are you following these recommendations? Style the sign-in page | Okta Developer If you are redirecting, are you customizing the Brand on your org for either your custom domain or base Okta domain, whichever one you are using as your issuer?