Increase subtitle text size from 1.25rem to 1.5rem

Author: adamgraham

src/base/tokens.css

@@ -84,7 +84,7 @@
   --text-title-lg: 2.25rem;
   --text-title-md: 1.75rem;
   --text-title-sm: 1.25rem;
-  --text-subtitle: 1.25rem;
+  --text-subtitle: 1.5rem;
   --text-body-lg: 1.125rem;
   --text-body-md: 1rem;
   --text-body-sm: .875rem;