diff --git a/app/internal/handlers/handlers.go b/app/internal/handlers/handlers.go
index 922d89b..897de89 100644
--- a/app/internal/handlers/handlers.go
+++ b/app/internal/handlers/handlers.go
@@ -70,6 +70,17 @@ func New(imagesDir, staticDir string, mailCfg *mail.Config) (*Server, error) {
 	} else {
 		log.Print("gallery thumbnails: ready")
 	}
+	// Thumbnail URLs are resolved during gallery.List. Re-list after derivative
+	// generation so newly-created thumbs appear immediately on first load.
+	if refreshed, err := gallery.List(imagesDir); err != nil {
+		log.Printf("gallery refresh after thumbnails: %v", err)
+	} else {
+		srv.Images = refreshed
+		if hero, hasHero := gallery.SelectHero(refreshed); hasHero {
+			srv.Hero = hero
+			srv.HasHero = true
+		}
+	}
 	return srv, nil
 }
 
diff --git a/app/templates/gallery.templ b/app/templates/gallery.templ
index d384c61..c518237 100644
--- a/app/templates/gallery.templ
+++ b/app/templates/gallery.templ
@@ -22,7 +22,9 @@ templ GalleryGrid(images []gallery.Image) {
 			>
 				if img.ThumbURL != "" {
 					<img
-						src={ img.ThumbURL }
+						src="data:image/gif;base64,R0lGODlhAQABAAD/ACwAAAAAAQABAAACADs="
+						data-src={ img.ThumbURL }
+						class="lazy-thumb"
 						alt={ fmt.Sprintf("%s — %s", gallery.AlbumLabel(img.Album), formatDate(img.Date)) }
 						loading="lazy"
 						decoding="async"
diff --git a/app/templates/layout.templ b/app/templates/layout.templ
index 87e6a7e..1aa4f5a 100644
--- a/app/templates/layout.templ
+++ b/app/templates/layout.templ
@@ -34,6 +34,47 @@ templ Layout(title string, preloadImage string, content templ.Component) {
 			</footer>
 			<div id="modal-root"></div>
 			<script src="/static/htmx.min.js" defer></script>
+			<script>
+				(function () {
+					function hydrateLazyThumbs(root) {
+						var lazyImages = root.querySelectorAll("img[data-src]");
+						if (!lazyImages.length) return;
+
+						if (!("IntersectionObserver" in window)) {
+							lazyImages.forEach(function (img) {
+								img.src = img.dataset.src;
+								img.removeAttribute("data-src");
+							});
+							return;
+						}
+
+						var observer = new IntersectionObserver(
+							function (entries) {
+								entries.forEach(function (entry) {
+									if (!entry.isIntersecting) return;
+									var img = entry.target;
+									img.src = img.dataset.src;
+									img.removeAttribute("data-src");
+									observer.unobserve(img);
+								});
+							},
+							{ rootMargin: "300px 0px" },
+						);
+
+						lazyImages.forEach(function (img) {
+							observer.observe(img);
+						});
+					}
+
+					document.addEventListener("DOMContentLoaded", function () {
+						hydrateLazyThumbs(document);
+					});
+
+					document.body.addEventListener("htmx:afterSwap", function (event) {
+						hydrateLazyThumbs(event.target);
+					});
+				})();
+			</script>
 		</body>
 	</html>
 }