When an SSL certificate is installed on a website, but the page also calls content from another website without an SSL certificate, the SSL certificate icon will turn grey instead of green:instead of:Their site Google Images is also protected with an SSL certificate, but it stays green:even though they call content (the images that are shown in the results) from websites without an SSL certificate.How is this possible?(Screenshots from my own question at Webmasters.SE)
How does Google manage their Google Images SSL certificate?
security;google;ssl
If you inspect the images with devtools, you will see that they don't use external urls, but instead use base64 encoded data uri's as the image source: