fix: mathematics cannot scroll horizontally (#760)

Author: cotes2020

_sass/addon/commons.scss

@@ -159,11 +159,6 @@ blockquote {
   @include prompt("danger", "\f071");
 }
 
-mjx-container {
-  overflow-x: auto;
-  overflow-y: hidden;
-}
-
 kbd {
   font-family: inherit;
   display: inline-block;
@@ -679,6 +674,12 @@ figure .mfp-title {
   text-align: center;
 }
 
+/* MathJax */
+mjx-container {
+  overflow-y: hidden;
+  min-width: auto !important;
+}
+
 /* --- sidebar layout --- */
 
 $sidebar-display: "sidebar-display";