Apply the Business Central look and feel
Apart from the functionality, an important aspect of creating a control add-in object is making sure that it looks good and blends seamlessly into Business Central. To achieve this aesthetic, you should follow these basic principles:
Apply similar patterns for command, navigation, and presentation of data.
Favor content over chrome.
Design for all platforms and input methods.
Make it accessible to all users.
Make it enjoyable and keep users in control.
Business Central uses a set of specific colors and fonts that you can use in your control add-in to give it a style that matches the rest of a client's user interface.
You can find the Control Add-in Style Guide in the online documentation.