Clean up CSS macros

Move the CSS macros into global macros, and allow the colour macro to
fallback to the vanilla palette if the required colour isn’t found in
the current palette.

core/ui/PageStylesheet.tid

@@ -1,59 +1,9 @@
 title: $:/core/ui/PageStylesheet
 
-\define colour(name)
-<$transclude tiddler={{$:/palette}} index="$name$"/>
-\end
-\define color(name)
-<<colour $name$>>
-\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)
-<$macrocall $name="makedatauri" type={{$title$!!type}} text={{$title$}}/>
-\end
-\define if-sidebar(text)
-<$reveal state="$:/state/sidebar" type="match" text="yes" default="yes">$text$</$reveal>
-\end
-\define if-no-sidebar(text)
-<$reveal state="$:/state/sidebar" type="nomatch" text="yes" default="yes">$text$</$reveal>
-\end
-
+<$importvariables filter="[[$:/core/ui/PageMacros]] [all[shadows+tiddlers]tag[$:/tags/Macro]!has[draft.of]]">
 
 <$list filter="[all[shadows+tiddlers]tag[$:/tags/stylesheet]!has[draft.of]]">
 <$transclude/>
 </$list>
+
+</$importvariables>

core/wiki/macros/CSS.tid

@@ -2,9 +2,63 @@ title: $:/core/macros/CSS
 tags: $:/tags/Macro
 
 \define colour(name)
-<$transclude tiddler={{$:/palette}} index="$name$"/>
+<$transclude tiddler={{$:/palette}} index="$name$"><$transclude tiddler="$:/palettes/Vanilla" index="$name$"/></$transclude>
 \end
 
 \define color(name)
 <<colour $name$>>
 \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)
+<$macrocall $name="makedatauri" type={{$title$!!type}} text={{$title$}}/>
+\end
+
+\define if-sidebar(text)
+<$reveal state="$:/state/sidebar" type="match" text="yes" default="yes">$text$</$reveal>
+\end
+
+\define if-no-sidebar(text)
+<$reveal state="$:/state/sidebar" type="nomatch" text="yes" default="yes">$text$</$reveal>
+\end