[Glitch] Use custom mascot on static share page

Port d499bb031f to glitch-soc

Signed-off-by: Claire <claire.github-309c@sitedethib.com>

app/javascript/flavours/glitch/styles/modal.scss

@@ -12,10 +12,19 @@
   flex-direction: column;
   justify-content: flex-end;
 
-  > * {
+  > div {
     flex: 1;
     max-height: 235px;
-    background: url('~images/elephant_ui_plane.svg') no-repeat left bottom / contain;
+    position: relative;
+
+    img {
+      max-height: 100%;
+      max-width: 100%;
+      height: 100%;
+      position: absolute;
+      bottom: 0;
+      left: 0;
+    }
   }
 }