Experiement to see if MathJax is rending correctly.

I was specifying the Neo-Euler font, which renders poorly
on nbviewer. This is a test to make sure it works before
checking in all notebooks. (I have to re-execute the notebook)
so that the script from the css file gets embedded into the
notebook).

code/custom.css

@@ -213,7 +213,7 @@
                     inlineMath: [ ['$','$'], ["\\(","\\)"] ],
                     displayMath: [ ['$$','$$'], ["\\[","\\]"] ]
                 },
-                displayAlign: 'left', // Change this to 'center' to center equations.
+                displayAlign: 'center', // Change this to 'center' to center equations.
                 "HTML-CSS": {
                     scale:100,
                         availableFonts: [],