Safari OS X: Fix Facebook web login buttons not working anymore

Here's a fix for Safari 8 on OS X Yosemite on how-to resolve the issues with the Facebook Single-Sign-On Login Buttons on websites not working anymore, due to a strict Cookie & website data restriction setting in Safari's Preferences.

Fix: Safari Private Browsing Greyed Out in Safari on iPhone, iPad - The Mac Observer

Is there a way for iPhone to open Facebook links in the Facebook App instead of Safari? - Quora

Apple releases Safari 14.1.2 for macOS Catalina and Mojave - 9to5Mac

Safari 15 now available for macOS Big Sur and Catalina users - 9to5Mac

Manage Website Push Notifications in Safari for OS X

Bypass 'Safari no longer supports the unsafe extension' in macOS – George Garside

Learn Sandbox - Sign in button not working - Microsoft Q&A

I am having trouble logging in with Google on Safari

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