Administrators can set a custom colour to be used in the draw.io menu bar that appears when you edit a diagram in Confluence Cloud by adding some CSS to the JSON configuration code in the draw.io Configuration settings. Setting a specific draw.io theme to be used by default whenever users create or edit a diagram is done in a similar way.
Set a custom menu colour and default theme
Go to the draw.io Configuration tab in the draw.io Configuration section of your Confluence Cloud settings.
Add the CSS code to customise the background colour of the menu bar.
Set a default theme: kennedy, atlas, dark or min. For example, users will see an orange menu bar and use the Kennedy theme by default with the following configuration code: