fix input color (#17)

frontend/src/components/WorkspaceChat/ChatContainer/PromptInput/index.jsx

@@ -63,7 +63,7 @@ export default function PromptInput({
               adjustTextArea(e);
             }}
             value={message}
-            className="cursor-text max-h-[100px] md:min-h-[40px] block mx-2 md:mx-4 p-2.5 w-full text-[16px] md:text-sm rounded-lg border bg-gray-50 border-gray-300 placeholder-gray-400 text-white dark:bg-stone-600 dark:border-stone-700 dark:placeholder-stone-400"
+            className="cursor-text max-h-[100px] md:min-h-[40px] block mx-2 md:mx-4 p-2.5 w-full text-[16px] md:text-sm rounded-lg border bg-gray-50 border-gray-300 placeholder-gray-400 text-gray-900 dark:text-white dark:bg-stone-600 dark:border-stone-700 dark:placeholder-stone-400"
             placeholder="Shift + Enter for newline. Enter to submit."
           />
           <button