Revert "delete mathjax"

This reverts commit a553fbc2.

layouts/shortcodes/header1.html

@@ -4,6 +4,32 @@
 <script defer data-domain="pntfx.com" src="https://plausible.io/js/plausible.js"></script>
 
 
+<script type="text/x-mathjax-config">
+  MathJax.Hub.Config({ "HTML-CSS": { width:"container", scale:100,linebreaks: { automatic: true } }, SVG: { linebreaks: { automatic: true } }});
+  MathJax.Hub.Queue(function () {
+    $(".collapse").removeClass("in");
+    });
+</script>
+<script>
+  (function () {
+    var head = document.getElementsByTagName("head")[0],
+      script;
+    script = document.createElement("script");
+    script.type = "text/x-mathjax-config";
+    script[window.opera ? "innerHTML" : "text"] =
+      "MathJax.Hub.Config({\n" +
+      " tex2jax: { inlineMath: [['$','$'], ['\\\\(','\\\\)']] }\n" +
+      "});";
+    head.appendChild(script);
+    script = document.createElement("script");
+    script.type = "text/javascript";
+    script.src =
+      "https://cdnjs.cloudflare.com/ajax/libs/mathjax/2.7.1//MathJax.js?config=TeX-AMS-MML_HTMLorMML";
+    head.appendChild(script);
+  })();
+</script>
+
+
 <script>
     let current_id = "{{ index .Params 0 }}";
   </script>