fix(style): improve MathJax and KaTeX (#707)

include/style/plugin.styl

@@ -80,3 +80,32 @@
  * --------------------------------- */
 .fa, .fab, .fal, .far, .fas
     line-height: inherit
+
+/* ---------------------------------
+ *       MathJax and KaTeX
+ * --------------------------------- */
+.MathJax, .katex-display
+    overflow-x: auto
+    overflow-y: hidden
+
+.katex
+    white-space: nowrap
+
+.katex-display
+    margin-top: -1em !important
+
+.katex-html
+    padding-top: 1em
+    .tag
+        align-items: unset
+        background-color: unset
+        border-radius: unset
+        color: unset
+        display: unset
+        font-size: unset
+        height: unset
+        justify-content: unset
+        line-height: unset
+        padding-left: unset
+        padding-right: unset
+        white-space: unset