<$set name="tv-config-toolbar-class" value="tc-btn-invisible">
{{$:/core/ui/Buttons/new-tiddler}}
</$set>
<$set name="tv-config-toolbar-class" value="green-background">
{{$:/core/ui/Buttons/new-tiddler}}
</$set>
The green-background CSS class is declared in a stylesheet within this tiddler.