Interface: HTTP server: set proper align when expanding menu buttons

Fixes #13855

The small menu buttons on the left doesn't move downwards anymore when
the menu is expanded
Signed-off-by: Jean-Baptiste Kempf <jb@videolan.org>

share/lua/http/css/main.css

@@ -107,6 +107,7 @@ body{
 }
 
 .buttonszone_active {
+	margin-top: 0px;
 	width: 120px;
 	margin-left:-122px;
 	font-size:10px;