fix: Broken secondary color

I belive this got replaced in 07ce8de, this reverts it back to its
previous state.

src/app.css

@@ -23,7 +23,7 @@
     --input: 20 5.9% 90%;
     --primary: 24 9.8% 10%;
     --primary-foreground: 60 9.1% 97.8%;
-    --secondary: 60 4.8% 95.9%;
+    --secondary: 240 6% 90%;
     --secondary-foreground: 24 9.8% 10%;
     --accent: 60 4.8% 95.9%;
     --accent-foreground: 24 9.8% 10%;