fix(#16): Solved that mathjax is not working properly

layout/_third-party/math/mathjax.pug

 script(type="text/x-mathjax-config").
   var mathjaxMhchem = '';
+  var mathJaxTex = {
+    equationNumbers: {
+      autoNumber: "AMS"
+    }
+  };
 
   if (!{ theme.math.mathjax.mhchem.enable }) {
     mathjaxMhchem = '!{ theme.math.mathjax.mhchem.mhchem_js }';
     MathJax.Ajax.config.path['mhchem'] = mathjaxMhchem;
+
+    mathJaxTex.extensions = [mathjaxMhchem];
+  } else {
+    mathJaxTex.extensions = ["AMSmath.js","AMSsymbols.js"];
   }
 
   MathJax.Hub.Config({
+    menuSettings: {
+      zoom: "None"
+    },
+    showMathMenu: false,
+    jax: ["input/TeX","output/CommonHTML"],
+    extensions: ["tex2jax.js"],
+    TeX: mathJaxTex,
     tex2jax: {
       inlineMath: [['$', '$'], ['\\(', '\\)']],
+      displayMath: [["\\[", "\\]"]],
       processEscapes: true,
       skipTags: ['script', 'noscript', 'style', 'textarea', 'pre', 'code']
-    },
-    TeX: {
-      extensions: [mathjaxMhchem],
-      equationNumbers: {
-        autoNumber: 'AMS'
-      }
     }
   });