diff --git a/docs/iframe-theme.js b/docs/iframe-theme.js
index 35287274c..07e44f82b 100644
--- a/docs/iframe-theme.js
+++ b/docs/iframe-theme.js
@@ -1,67 +1,65 @@
 (function () {
+  const PROCESSED_ATTR = "data-theme-listener-added";
+
   function updateIframesForDarkMode() {
     const isDark = document.documentElement.classList.contains("dark");
 
-    document.querySelectorAll('iframe[src*="chromatic.com/iframe.html"]').forEach((iframe) => {
-      iframe.style.background = "transparent";
-      iframe.allowTransparency = true;
+    document
+      .querySelectorAll('iframe[src*="chromatic.com/iframe.html"]')
+      .forEach((iframe) => {
+        iframe.style.background = "transparent";
+        iframe.allowTransparency = true;
 
-      // Use postMessage to communicate with the iframe since we can't access contentDocument due to CORS
-      const sendThemeMessage = () => {
-        try {
-          const message = {
-            type: 'THEME_CHANGE',
-            isDark: isDark,
-            styles: {
-              background: isDark ? '#0b0d0f' : 'transparent' // transparent for light mode
-            }
-          };
-          iframe.contentWindow.postMessage(message, '*');
-        } catch (e) {
-          console.warn("Could not send message to iframe:", e);
-        }
-      };
+        const sendThemeMessage = () => {
+          try {
+            const message = {
+              type: "THEME_CHANGE",
+              isDark: isDark,
+              styles: {
+                background: isDark ? "#0b0d0f" : "transparent",
+              },
+            };
+
+            const targetOrigin = new URL(iframe.src).origin;
+            iframe.contentWindow.postMessage(message, targetOrigin);
+          } catch (e) {
+            console.warn("Could not send message to iframe:", e);
+          }
+        };
 
-      // Send message immediately if iframe might be loaded
-      sendThemeMessage();
+        // Prevent adding multiple event listeners
+        if (!iframe.hasAttribute(PROCESSED_ATTR)) {
+          iframe.addEventListener("load", () => {
+            setTimeout(sendThemeMessage, 100);
+          });
+          iframe.setAttribute(PROCESSED_ATTR, "true");
+        }
 
-      // Also send message when iframe loads
-      iframe.addEventListener("load", () => {
-        // Add a small delay to ensure iframe is ready
-        setTimeout(sendThemeMessage, 100);
+        // Initial message send
+        sendThemeMessage();
       });
-    });
   }
 
-  // Listen for theme changes on the parent document
   const observer = new MutationObserver((mutations) => {
-    mutations.forEach((mutation) => {
-      if (mutation.type === 'attributes' && 
-          mutation.attributeName === 'class' && 
-          mutation.target === document.documentElement) {
+    for (const mutation of mutations) {
+      if (
+        mutation.type === "attributes" &&
+        mutation.attributeName === "class" &&
+        mutation.target === document.documentElement
+      ) {
         updateIframesForDarkMode();
       }
-    });
+    }
   });
 
   observer.observe(document.documentElement, {
     attributes: true,
-    attributeFilter: ['class']
+    attributeFilter: ["class"],
   });
 
   if (document.readyState === "loading") {
     document.addEventListener("DOMContentLoaded", updateIframesForDarkMode);
   } else {
-    setTimeout(updateIframesForDarkMode, 100);
-    // TODO: add Storybook with Darkmode enabled
-    let themeChangeCount = 0;
-    const themeChangeInterval = setInterval(() => {
-      if (themeChangeCount < 2) {
-        updateIframesForDarkMode();
-        themeChangeCount++;
-      } else {
-        clearInterval(themeChangeInterval);
-      }
-    }, 1000);
+    updateIframesForDarkMode();
   }
 })();