I came across this question, where I saw this:
It looks like some sort of CSS issue, and it may have to do with the new MathJax 2.3 beta. However, I vaguely recall seeing this type of rendering glitch before -- which is why I didn't post as an answer there.
I used Windows 7 Pro SP1, x64, and Chrome 30.0.x to produce this image.
\begin{align}...\end{align}
(i.e., no encompassing dollar signs, though adding them doesn't help) that have no new lines, and no aligning&
. Adding the ampersand fixes the issue. Zooming also has strong effects -- the padding varies wildly and without pattern. $\endgroup$&
at the end, which then pushes symbols out of view to the left. (Clearing cache etc. didn't work.) $\endgroup$