Note: You will need to have at least LiveProject Premium Viewer to use this feature. To use the shared server options, you will need at least LiveProject Team Viewer. Compare versions.
You can configure the text styles for you Calendar view by selecting the context sensitive menu Calendar Settings > Zoom
Just select the item (e.g. non-critical tasks or monthly titles) and click Change Font to configure the text style for that particular item.
As you make changes you can see the effect your changes will have on the calendar in the sample provided.