.

components/CookieBanner.tsx

@@ -22,7 +22,7 @@
 // =============================================================================
 
 import Link from "next/link";
-import { useEffect, useState } from "react";
+import { useEffect, useLayoutEffect, useState } from "react";
 import { site } from "@/content";
 
 const CONSENT_KEY = "novarix-cookie-consent";
@@ -33,30 +33,20 @@ const INTRO_EVENT = "novarix:start-intro";
 type Consent = "unknown" | "ack" | "rst";
 
 export default function CookieBanner() {
-  // Start from the pre-hydration decision made in layout.tsx so the banner
-  // can appear immediately on first visit without waiting for a delayed effect.
-  const [visible, setVisible] = useState(() => {
-    if (typeof document === "undefined") return false;
-    return document.documentElement.dataset.showCookieBanner === "1";
-  });
+  // Hidden by default on the server, then synchronously shown on first paint
+  // if no consent choice exists yet.
+  const [visible, setVisible] = useState(false);
 
   // Read the stored consent on mount and decide whether to show the banner.
-  useEffect(() => {
+  useLayoutEffect(() => {
     try {
       const stored = window.localStorage.getItem(CONSENT_KEY) as Consent | null;
       if (stored !== "ack" && stored !== "rst") {
-        document.documentElement.dataset.showCookieBanner = "1";
-        // eslint-disable-next-line react-hooks/set-state-in-effect
         setVisible(true);
-      } else {
-        document.documentElement.dataset.showCookieBanner = "0";
       }
     } catch {
       // localStorage unavailable (private mode, blocked, etc.) — show the
-      // banner so the user is still told. Sync-once-on-mount is a legitimate
-      // use of setState in an effect.
-      // eslint-disable-next-line react-hooks/set-state-in-effect
-      document.documentElement.dataset.showCookieBanner = "1";
+      // banner so the user is still told.
       setVisible(true);
     }
   }, []);
@@ -80,7 +70,6 @@ export default function CookieBanner() {
     } catch {
       /* storage unavailable — nothing to do */
     }
-    document.documentElement.dataset.showCookieBanner = "0";
     setVisible(false);
   }