Mixed Content Examples

The pages […] allow you to see different types of mixed content and test how they behave in your browser. The "Secure" pages are referencing assets with HTTPS, the "Non-Secure" pages are referencing them with HTTP. Generally, you'll observe the same behavior with both Secure pages and the Secure HTTP page for a given test; the behavior will change on the Non-Secure HTTPS page.

Also see Testing HTTPS with badssl.com.