This page loads an external ssl css file, which in turn loads a non-ssl (unencrypted) ssl file.

CSS to separate Firefox 22 and 23 using ssl loading capabilities:
Version 23 for security reasons removed the ability to load a non-secure page from within a secure page.
Loading a ssl-encrypted css page which in turn loads an unencrypted css page does this.
All modern web browsers (Chrome, Safari) already do this, so to specify only firefox, extra css is required.
The Firefox 23+ version may not load in time from a remote site to render properly (possible race condition)
though within a site that serves up both http and https pages it appears to work effectively.
Reference: https://developer.mozilla.org/en-US/Firefox/Releases/23

Detected browsers will show in red, otherwise gray below.

Firefox 23+
Firefox 23
Firefox 22

CSS Hack written by Jeff Clayton (https://jeffclayton.wordpress.com)