Remove polyfill.io (#417) (#420)

docs/javascripts/mathjax.js

@@ -0,0 +1,19 @@
+window.MathJax = {
+    tex: {
+      inlineMath: [["\\(", "\\)"]],
+      displayMath: [["\\[", "\\]"]],
+      processEscapes: true,
+      processEnvironments: true
+    },
+    options: {
+      ignoreHtmlClass: ".*|",
+      processHtmlClass: "arithmatex"
+    }
+  };
+
+  document$.subscribe(() => { 
+    MathJax.startup.output.clearCache()
+    MathJax.typesetClear()
+    MathJax.texReset()
+    MathJax.typesetPromise()
+  })

mkdocs.yaml

@@ -54,6 +54,7 @@ plugins:
   - mike:
 
 markdown_extensions:
+  # https://squidfunk.github.io/mkdocs-material/reference/math/?h=math#mathjax
   - pymdownx.arithmatex:
       generic: true
   - pymdownx.superfences
@@ -63,8 +64,8 @@ markdown_extensions:
   - admonition
 
 extra_javascript:
-  - https://polyfill.io/v3/polyfill.min.js?features=es6
-  - https://cdn.jsdelivr.net/npm/mathjax@3/es5/tex-mml-chtml.js
+  - javascripts/mathjax.js
+  - https://unpkg.com/mathjax@3/es5/tex-mml-chtml.js
 
 extra:
   version: