You are doing it correctly.
The call to gravatar.com passes the location of your custom image so that WP can load it. Take a look at the query string in the src, you’ll see your image location. That’s how it works.
You are doing it correctly.
The call to gravatar.com passes the location of your custom image so that WP can load it. Take a look at the query string in the src, you’ll see your image location. That’s how it works.