Correct wrong value for background-color

src/assets/stylesheets/base/_typeset.scss

@@ -251,7 +251,7 @@ kbd {
     // Reset, if code is inside pre
     > code {
       margin: 0;
-      background-color: none;
+      background-color: transparent;
       font-size: inherit;
       box-shadow: none;
       box-decoration-break: none;