I've followed Adding the HTML sign-in button to your page instructions, and made it work in my development environment. At production I need to support subdomains, but I can't make it work. I've changed data-cookiepolicy from single_host_origin to https://mydomain.com as API reference says, so this way it should support login from https://mysubdomain.mydomain.com. I've also added https://mydomain.com to Javascript origins at Google Developer Console. Nevertheless, when I click Login button, after authentication step, a 400 error is displayed, with Error: origin_mismatch message. It works if I add the url with the subdomain to the Javascript origin list, but that's not what I need, since I don't know them in advance (and might be tons).
What might I missing? Thanks! :_(