Astah System Safety provides plenty of light/dark themes since version 8.0.
You can choose your preferred theme to apply to Astah System Safety from [View] – [Look & Feel] in main menu.
Currently, themes do not apply to diagram editor’s background color. If you want to tune it up to fit the dark surface, you can change it from [Tools] – [System Properties] – [Basic] – [Diagram Editor] – [Background color].
There are nearly 70 pre-installed themes you can choose from. Here’re the previews of each one of them.
Or you can see the best 8 themes we recommend.
To see all available themes, please pick the category.