Update column styles to enhance background visibility and maintain consistency

Author: ManukMinasyan

resources/css/flowforge.css

@@ -94,7 +94,7 @@
  * Contains header with title and count, and scrollable content area
  */
 .ff-column {
-    @apply w-[300px] min-w-[300px] flex-shrink-0 border border-gray-200 dark:border-gray-700 shadow-sm dark:shadow-md rounded-xl flex flex-col max-h-full overflow-hidden;
+    @apply w-[300px] min-w-[300px] bg-white/30 flex-shrink-0 border border-gray-200 dark:border-gray-700 shadow-sm dark:shadow-md rounded-xl flex flex-col max-h-full overflow-hidden;
 
     &__header {
         @apply flex items-center justify-between py-3 px-4 border-b border-gray-200 dark:border-gray-700;