Swipebox slide background gradient of black to blue, so that back SVG images are visible.

Thanks to xet7 !

client/components/cards/attachments.css

@@ -1,3 +1,8 @@
+.slide {
+  /* swipebox slide background gradient of black to blue, so that back SVG images are visible */
+  background: rgb(2,0,36);
+  background: linear-gradient(90deg, rgba(2,0,36,1) 0%, rgba(9,9,121,1) 14%, rgba(0,212,255,1) 100%); 
+}
 .attachment-upload {
   text-align: center;
   font-weight: bold;