@startuml
<style>
  title {
    BackGroundColor transparent
    FontColor black
    HorizontalAlignment center
  }  
</style>
label l [
{{
!theme crt-green
title crt-green
Alice -> Bob: crt-green
Bob -> Alice: crt-green
}}
{{
title ___________________________________  
}}
{{
!theme cyborg-outline
title cyborg-outline
Alice -> Bob: cyborg-outline
Bob -> Alice: cyborg-outline
}}
{{
title ___________________________________  
}}
{{
!theme cyborg
title cyborg
Alice -> Bob: cyborg
Bob -> Alice: cyborg
}}
{{
title ___________________________________  
}}
{{
!theme hacker
title hacker
Alice -> Bob: hacker
Bob -> Alice: hacker
}}
{{
title ___________________________________  
}}
{{
!theme lightgray
title lightgray
Alice -> Bob: lightgray
Bob -> Alice: lightgray
}}
{{
title ___________________________________  
}}
{{
!theme mars
title mars
Alice -> Bob: mars
Bob -> Alice: mars
}}
{{
title ___________________________________  
}}
{{
!theme materia-outline
title materia-outline
Alice -> Bob: materia-outline
Bob -> Alice: materia-outline
}}
{{
title ___________________________________  
}}
{{
!theme materia
title materia
Alice -> Bob: materia
Bob -> Alice: materia
}}
{{
title ___________________________________  
}}
{{
!theme metal
title metal
Alice -> Bob: metal
Bob -> Alice: metal
}}
{{
title ___________________________________  
}}
{{
!theme mimeograph
title mimeograph
Alice -> Bob: mimeograph
Bob -> Alice: mimeograph
}}
{{
title ___________________________________  
}}
]
@enduml