The latest Firefox beta, version 23, blocks all mixed content by default.
I discovered that the blog section of the website has many css references which are now blocked causing the site to not look so great.

In addition, there is a 404 error at the end for an additional CSS reference.

Here is my console log from Firefox.

[09:50:31.189] GET https://blog.mariadb.org/state-of-the-sea-lion/ [HTTP/1.1 200 OK 593ms]
[09:50:31.719] Blocked loading mixed active content "http://blog.mariadb.org/wp-content/plugins/twitter-facebook-google-plusone-share/tfg_style.css?ver=3.5.2" @ https://blog.mariadb.org/state-of-the-sea-lion/
[09:50:31.724] Blocked loading mixed active content "http://blog.mariadb.org/wp-content/themes/the-bootstrap/css/bootstrap.min.css?ver=2.0.3" @ https://blog.mariadb.org/state-of-the-sea-lion/
[09:50:31.725] Blocked loading mixed active content "http://blog.mariadb.org/wp-content/themes/the-bootstrap/style.min.css?ver=0.1.0" @ https://blog.mariadb.org/state-of-the-sea-lion/
[09:50:31.725] Blocked loading mixed active content "http://blog.mariadb.org/wp-content/themes/mariadb/style.css?ver=3.5.2" @ https://blog.mariadb.org/state-of-the-sea-lion/
[09:50:31.725] Blocked loading mixed active content "http://blog.mariadb.org/wp-includes/js/jquery/jquery.js?ver=1.8.3" @ https://blog.mariadb.org/state-of-the-sea-lion/
[09:50:31.725] Blocked loading mixed active content "http://blog.mariadb.org/wp-content/plugins/google-analyticator/external-tracking.min.js?ver=6.4.4.3" @ https://blog.mariadb.org/state-of-the-sea-lion/
[09:50:31.725] Blocked loading mixed active content "http://platform.twitter.com/widgets.js?ver=3.5.2" @ https://blog.mariadb.org/state-of-the-sea-lion/
[09:50:31.725] Blocked loading mixed active content "http://apis.google.com/js/plusone.js?ver=3.5.2" @ https://blog.mariadb.org/state-of-the-sea-lion/
[09:50:31.725] Blocked loading mixed active content "http://platform.linkedin.com/in.js?ver=3.5.2" @ https://blog.mariadb.org/state-of-the-sea-lion/
[09:50:31.725] Blocked loading mixed active content "http://assets.pinterest.com/js/pinit.js?ver=3.5.2" @ https://blog.mariadb.org/state-of-the-sea-lion/
[09:50:31.725] Blocked loading mixed active content "http://blog.mariadb.org/wp-content/themes/the-bootstrap/js/bootstrap.min.js?ver=2.0.3" @ https://blog.mariadb.org/state-of-the-sea-lion/
[09:50:31.725] Blocked loading mixed active content "http://blog.mariadb.org/wp-content/themes/the-bootstrap/js/the-bootstrap.min.js?ver=0.1.0" @ https://blog.mariadb.org/state-of-the-sea-lion/
[09:50:32.151] GET https://mariadb.org/static/main-cccc5b9c0951bfe8f347aa02c774872d29c8e5bc.css [HTTP/1.1 404 Not Found 328ms]