If you are creating themes for your Power BI reports, you already know it can be challenging as there is not a lot of information describing how the JSON file theme should be built.
The following report contains 6 tabs (one is hidden) to not only help you create your theme files easier, but also to use it as a guideline for your theme in your organization.
The following elements can you find in the report.:

The Welcome Page, is your home page with links to all the resources available in the report. Just click on the images to go to different tabs and start customizing your theme.
The Labels Page, will allow you to search for Power BI visuals to find what labels are available for them. The labels are displayed in the same order as they appear in Power BI. Once you find the label you are looking for , right-click to go to the Properties Page, where all properties and values are listed.
The Properties Page, is hidden as it is used as a drillthrough for the Labels Page. Here you can see the name of the properties in the JSON file and the type you use for them. Once you are done, click the back arrow to go back to the Labels Page.
The Bulk Page, will allow you to search for visuals, labels or properties without having to go to the Label Pages. It can also list all the visuals that have a specific property if you want to do bulk editing.
The Font Page, will show the JSON name for the fonts and show you the default fonts for the Curbal theme.
and finally, the Color Page, will list all the colors available for this theme and give you their HEX code as well as some best practices.

Note, if you would like to customize this JSON Theme Guide, it is available for purchase here.
You can also purchase the complete JSON file used in this report here.

JSON Theme Guide for Power BI by Curbal

par Curbal AB