Fix problem with CSS macros

In practice the macros are always invoked in inline mode, meaning that
the triple braces weren’t getting parsed correctly. Now we switch to
inline code

core/wiki/macros/CSS.tid

@@ -10,45 +10,45 @@ tags: $:/tags/Macro
 \end
 
 \define box-shadow(shadow)
-```
+``
   -webkit-box-shadow: $shadow$;
      -moz-box-shadow: $shadow$;
           box-shadow: $shadow$;
-```
+``
 \end
 
 \define filter(filter)
-```
+``
   -webkit-filter: $filter$;
      -moz-filter: $filter$;
           filter: $filter$;
-```
+``
 \end
 
 \define transition(transition)
-```
+``
   -webkit-transition: $transition$;
      -moz-transition: $transition$;
           transition: $transition$;
-```
+``
 \end
 
 \define transform-origin(origin)
-```
+``
   -webkit-transform-origin: $origin$;
      -moz-transform-origin: $origin$;
           transform-origin: $origin$;
-```
+``
 \end
 
 \define background-linear-gradient(gradient)
-```
+``
 background-image: linear-gradient($gradient$);
 background-image: -o-linear-gradient($gradient$);
 background-image: -moz-linear-gradient($gradient$);
 background-image: -webkit-linear-gradient($gradient$);
 background-image: -ms-linear-gradient($gradient$);
-```
+``
 \end
 
 \define datauri(title)