Can see nothing but only black screen

[richaction]

Can see nothing but only black screen, no other actions can do. just follow the steps with ReadMe.

dfx version: dfx 0.7.0
browser: chrome 90.0.4430.212
operating system: macOS 10.15.7

[evilester]

try http://localhost:8000/sign-in?canisterId=xxxx-xxxx-xxxxx-xxxx
http://xxx-xxx-xxx-xxx.localhost:8000 has been blocked by CORS policy