I tested this short example on your Web Server
@startuml
skinparam class {
FontColor<<Serializable>> Blue
FontSize<<Serializable>> 16
FontStyle<<Serializable>> bold
BackgroundColor<<Serializable>> Turquoise
BorderColor<<Serializable>> Blue
}
hide <<Serializable>> stereotype
skinparam stereotypeCBackgroundColor<< Serializable >> Blue
'ok! S in red, default skin of class, no stereotype
class Dummy1 <<(S,Red)>> {
String name
}
'ok! C in blue, changed skin of stereotyped class, no display of stereotype
class Dummy2 <<Serializable>> {
String name
}
'ok! S in red, changed skin of stereotyped class, no display of stereotype
class Dummy3 <<(S,Red)>> <<Serializable>> {
String name
}
'??? S in red, changed skin of stereotyped class, but display of stereotype!?!?
class Dummy4 <<(S,Red) Serializable>> {
String name
}
'ok! stereotype not recognized!
class Dummy5 <<Serializable (S,Red)>> {
String name
}
@enduml
My question: is this result correct or shouldn‘t Dummy4 look like Dummy3?