A 
Theme provides styling rules, web resouces, fonts, a UI framework and a colour palette that your 
Pages can use.
A Theme can be created by right-clicking in the Entites tree and selecting New > Theme. In the resulting Create New Theme dialog you can create a blank Theme or download one from the Verj.io Resource Hub.
Using the same Theme in all your Pages ensures a consistant tone across your application and makes changing the look of your entire application easy.
To help with this, a Theme can be added to all of your 
Projects and their 
Forms configured to use their Project's Theme. Any changes to that Theme, including configuring the Projects to use a different Theme, automatically affect all Forms and their Pages.
A Theme can be added to a Project by right-clicking on it in the Entities tree and selecting 
Properties. Also, when creating a new Project an existing Theme in your Workspace can be selected, or a new one downloaded from the Resource Hub.
This behaviour can be customised for each Workspace by clicking on File > 
Workspace Preferences in the top menu.