- PlantUML does not natively support enforcing exact equal widths for partitions through CSS or other settings.
- The width of partitions is primarily determined by their content, so manual adjustments (like adding placeholders) may be necessary.
- Manual tweaking is probably required.

@startuml
partition "Partition 1" {
: Activity 1 ;
}
partition "Partition 2" {
:Activity 2 with a longer description;
}
partition "Partition 3" {
: Activity 3 ;
}
@enduml