diff --git a/falcon/_dev/js/theme/index.js b/falcon/_dev/js/theme/index.js
index 323fef8..0215387 100644
--- a/falcon/_dev/js/theme/index.js
+++ b/falcon/_dev/js/theme/index.js
@@ -66,6 +66,22 @@ function initStickyHeader() {
     }
 }
 
+// Sync product thumbs height with main images height
+function syncThumbsHeight() {
+    const mainImages = document.querySelector(".product-main-images");
+    const thumbs = document.querySelector(".product-thumbs.swiper");
+    // Only apply if Swiper is vertical
+    if (mainImages && thumbs && thumbs.classList.contains("swiper-vertical")) {
+        thumbs.style.maxHeight = mainImages.offsetHeight + "px";
+        thumbs.style.height = mainImages.offsetHeight + "px";
+    } else {
+        return;
+    }
+}
+
+window.addEventListener("load", syncThumbsHeight);
+window.addEventListener("resize", syncThumbsHeight);
+
 $(() => {
     initStickyHeader();
     accLinksTriggerActive();