dynamic video loading

frontend/css/style.css

@@ -1431,6 +1431,14 @@ body.feed-mode-open .mode-toggle-btn .icon-svg {
     height: 1px;
 }
 
+/* Stands in for the slides above the rendered window so scroll position and
+   snap points stay stable while slides are virtualized in and out. */
+.feed-top-spacer {
+    width: 100%;
+    height: 0;
+    flex: none;
+}
+
 .feed-slide {
     position: relative;
     width: 100%;