昔の ヘッダに <script type="text/javascript" src="https://cdnjs.cloudflare.com/ajax/libs/mathjax/2.7.0/MathJax.js?config=TeX-AMS_HTML"></script><script type="text/x-mathjax-config"> MathJax.Hub.Config({ tex2jax: { inlineMath: [["\\(","\\)"] ], displayMath: [ ['$$','$$'], ["\\[","\\]"] ] }, CommonHTML: { m…