Those circles are actually interface, so you can have:
@startuml
hide stereotype
<style>
document {
BackgroundColor LightGreen
}
interface {
BackGroundColor #ff3311
Shadowing 0
}
</style>
circle test
package {
circle ME100 <<failedval>>
circle ART213
ME100 -d-> ART213
}
@enduml
Sorry about the lack of documentation!