diff --git a/share/tools/web_config/fishconfig.css b/share/tools/web_config/fishconfig.css
index 2097eca62..a43bc07c4 100644
--- a/share/tools/web_config/fishconfig.css
+++ b/share/tools/web_config/fishconfig.css
@@ -438,6 +438,10 @@ img.delete_icon {
 	text-overflow: ellipsis;
 }
 
+.prompt_demo {
+    white-space: pre;
+}
+
 .unbordered {
 	border: none;
 	padding-top: 0;