When viewing a Stack Exchange site such as Math.SE which uses MathJax for LaTeX rendering, using Safari on Mac OS X 10.7, it produces an incorrect rendering which appears to make everything which should be upright italic and everything which should be italic “double italic”.
In this example, everything except the second and third
foo should be upright.
According to Strange LaTeX fonts in OS/X Lion? at Meta.Math.SE, a workaround is to disable the new STIX fonts in Mac OS X. However, this is not something Stack Exchange should require of users, so I request that a fix (if it’s MathJax’s problem) or workaround (if it’s Mac OS X’s problem) be implemented in the Stack Exchange MathJax.