add_action() – Function | Developer.WordPress.org
Adds a callback function to an action hook.| WordPress Developer Resources
Sharing Debugger lets you preview how your content will look when it's shared to Facebook and debug any issues with your Open Graph tags.| developers.facebook.com
Adds a callback function to an action hook.| WordPress Developer Resources
How to create a complex but highly customizable background gradient that can be modified easily using CSS custom properties.| Space Ninja
