Notice Google+ API is shutting down on March 7th, 2019.
A demo site showing a few tricks for improving the Google+ sign in experience.
To try the site out:
Create a Google APIs Console project, OAuth 2.0 client ID, enable the Google+ service, and register your JavaScript origins.
Replace YOUR_CLIENT_ID in index.html with the client id you set up in Step 1.
Either copy the folder to your web server or start a local web server. I personally find the Python built-in server to be great for testing. To start it on port 8000, run:
python -m SimpleHTTPServer 8000