LaTeX brackets don't display correctly (jsMath)

Question

I'm currently working with OLAT (a java based web application to manage lectures) and try to write some text containing LaTeX code inside (there is a html text editor which allows the use of LaTeX formulas via jsMath). When I try to display large brackets around a vector (with more than two rows), schematically :
<pre><nowiki>\begin{pmatrix}
x_1 \\ x_2 \\ x_3
\end{pmatrix}</nowiki></pre>
, the brackets aren't visible and there are some symbols instead (look at the screenshots). For shorter vectors (up to two rows), the problem doesn't appear.
Note that I encounter this problem on Firefox 27.0.1, both on Linux (Kubuntu 13.10) and Windows (7), but for instance not with other browsers (chromium, rekonq, etc.). Interestingly, someone tried this on a 27.0.01 version of Firefox under Archlinux, and the large brackets seems to be displayed correctly. It also seems to be working on Internet Explorer 9, 10 and 11.

Answer 1

Well, the page inspector seemed indeed to indicate that those specific jsMath fonts were required... and it solves the problem ! Shame on me not to have checked that additional point... And thank you for your help !
So for anyone encountering the same problem, you just have to install the missing jsMath fonts available here :
http://www.math.union.edu/~dpvc/jsmath/download/jsmath-fonts.html
However, there's still something that I don't quite understand : without the jsMath fonts installed on my OS, the page displayed correctly within some other browsers running on the same machine, is there a particular explanation or does Firefox work in a different way when it comes to those font problematics ?