docs: tweak mobile style of compatibility notification

Author: ulivz

Diff for: packages/docs/docs/.vuepress/styles/index.styl

@@ -25,7 +25,7 @@
       text-decoration underline
 
 @media (max-width: $MQMobile)
-  .compatibility-notification
+  .toasted-container.compatibility-notification
     &.top-right
       right 5vw
     .toasted