fix(gallery): add overflow hidden to prevent scrolling

Ensure the fixed gallery modal doesn't allow overflow beyond viewport.

Signed-off-by: Sped0n <hi@sped0n.com>

assets/scss/_partial/_gallery.scss

@@ -4,6 +4,7 @@
   position: fixed;
   top: var(--nav-height);
   z-index: var(--z-nav-gallery);
+  overflow: hidden;
 
   display: flex;
   flex-direction: column;