You now have the ability to set a Mekko Graphics chart to be optimized for a presentation with a dark background. This means that the chart will adjust its axis and line colors to white in order to accommodate for presentations with a dark background.
To do this choose the Dark Background button from the Mekko Graphics tab in PowerPoint. Choosing this button will cause it to highlight, indicating that any new chart in the presentation will have dark background optimization.
Once selected, if you edit an existing chart, the axis and line colors will change to a white color for better display on a slide with a dark background.
If you wish all existing charts in your presentation to be optimized for dark backgrounds, select this button and then you can simply choose the button Update All Charts, which will automatically update all charts in your deck to the dark background setting.
If you wish to remove this setting for your presentation, simply select it again and it will turn off. The highlight on the button will be removed. If you now edit an existing chart, the axis, border, and line colors will be reset to dark to better display on a slide with a white background.