Cropped reference on sequence diagram

Question

Hello PlantUML Team,

Just FYI, if the ref is the first element on a sequence, the ref. is cropped on the top (on PNG output).

Here is an example:

@startuml
scale 2
<style>
sequenceDiagram {
  reference {
    LineThickness 5
  }
}
</style>
ref over Alice, Bob : this is a reference\n(normal style)
@enduml

Regards,
Th.