[Glitch] Fix scrolling in single-column mode on Chrome

Port fb1b710e8d to glitch-soc

Signed-off-by: Thibaut Girka <thib@sitedethib.com>

app/javascript/flavours/glitch/styles/components/single_column.scss

@@ -129,6 +129,10 @@
 
   .scrollable {
     overflow: visible;
+
+    @supports(display: grid) {
+      contain: content;
+    }
   }
 
   @media screen and (min-width: $no-gap-breakpoint) {