bug fix

gallery-container.html

@@ -21,7 +21,7 @@
   <img src="gallery/20.jpg" alt="Image 20">
   <img src="gallery/21.gif" alt="Image 21">
   <img src="gallery/22.jpg" alt="Image 22">
-  <img src="gallery/23.png" alt="Image 23">
+  <img src="gallery/23.jpg" alt="Image 23">
   <img src="gallery/24.jpg" alt="Image 24">
   <img src="gallery/25.jpg" alt="Image 25">
   <img src="gallery/26.jpg" alt="Image 26">