When you visit a Secure website in Firefox chances are that the FavIcon for the website is replaced with a Green bar with the details of the company. This is because of the default properties in Firefox to display detailed information of the website from the Extended Validation Certificate on the website. However, if the website doesn’t host a Extended Validation certificate then the website URL (link) in the address bar is not highlighted or in otherwords shows as a normal website URL.
However, just to give you that extra highlighting of a website thats claims to be secure, you can choose to display the website domain or the subdomain highlighted in a Blue background next to the FavIcon of the website.
To do so, open a Firefox browser and type “about:config” in the address bar and press enter. Click the button “I’ll be careful, I promise!” button.
Type “browser.identity.ssl_domain_display” in the filter. Double-click the entry and set the following values:
1 – Show the top level domain (ex: google.com)
2 – Show the full domain including the subdomain (ex: www.google.com)