>>I go on a specific site on the site, which is a secure site. I see https on top with the lock on the right. When I am in the Web page, I see the URL changing with a green background. What is causing that and how do they do that?
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>Who do you mean by 'they' ? Sounds like it is browser or add-in specific - so, if so, which browser?

I see this in Google Chrome when I go to secure sites.