Chore: remove custom variant duplicate (#418)

Author: rin-st

templates/base/packages/nextjs/styles/globals.css.template.mjs

@@ -5,8 +5,6 @@ const contents = ({ postContent }) =>
 
 @custom-variant dark (&:where([data-theme=dark], [data-theme=dark] *));
 
-@custom-variant dark (&:where([data-theme=dark], [data-theme=dark] *));
-
 @theme {
   --shadow-center: 0 0 12px -2px rgb(0 0 0 / 0.05);
   --animate-pulse-fast: pulse 1s cubic-bezier(0.4, 0, 0.6, 1) infinite;