HTTPS and stylesheet problem

Since Firefox 36.0 was updated, it seems to have got more picky.

When I load the site, I get this error:

Blocked loading mixed active content “http://alteregovoices.com/?raindrops_color_type=1&ver=7a65286be6a584975b5d99dd52bff367”

https://alteregovoices.com

(Chrome and IE still load ok)

I have gone through and deactivated all my plugins, so I know it’s nothing to do with them.

Thank you in advance for any advice.

https://wordpress.org/plugins/wordpress-https/