refactor: check

Author: Andrew Seguin

src/material/core/theming/_definition.scss

@@ -54,7 +54,7 @@ $theme-version: 1;
 
   // typography
   $default-plain: (Roboto, sans-serif);
-  $default-brand: $plain;
+  $default-brand: $default-plain;
   $plain: map.get($typography-config, plain-family) or $default-plain;
   $brand: map.get($typography-config, brand-family) or $default-brand;
   $bold: map.get($typography-config, bold-weight) or 700;