diff --git a/For-Friendica-Users.md b/For-Friendica-Users.md
index 21fda84..8fd12ca 100644
--- a/For-Friendica-Users.md
+++ b/For-Friendica-Users.md
@@ -278,6 +278,9 @@ Solid color names are being normalized to HTML color names. The old names are in
 - .postbox-violetblue
 
 **Pattern Backgrounds:**
+
+The patterns are accomplished with pure CSS code. There are no images involved.
+
 ![pattern_backgrounds](uploads/27b0e36bef337885e0bb76329d979ba3/pattern_backgrounds.png)
 - .postbox-blueprint
 - .postbox-birds
@@ -298,7 +301,9 @@ Solid color names are being normalized to HTML color names. The old names are in
 - .postbox-wavy
 
 **Animated Backgrounds:**
-These are ONLY available on servers with the _Postbox_ or _Zen Postbox_ add-on installed.
+
+These are ONLY available on servers with the _Postbox_ or _Zen Postbox_ add-on installed. The animations use SVG images and CSS and should work in all modern browsers, but may not work or work well in older browsers or on mobile devices.
+
 ![animated_backgrounds](uploads/25c7acabde882d54160b2e4e0fe54d1b/animated_backgrounds.png)
 - .postbox-anigradient
 - .postbox-blob