When the first Theme is selected it automatically gives the Predefined Style for Tabs but if you want to Customize Tabs you can follow this guide.
- Drag and Drop Tabs from left side widget section then a Dialogue Box will pop up by this action for Tabs as shown in image below .
- Now in Settings section of Dialog Box you can open Tab and add text of your own as shown in image below.
- In Settings section of Dialogue Box you can also select icons and customize as shown in figure below.
- Now in Style section of Dialog Box you can give Custom Style and also use Predefined Styles as shown in image below.