Ability to define the border gradient (for the 'bevel' effect)

Would be lovely to have this feature, now the border is one-coloured. The gradient will create nice bevel effect.

<img width="134" alt="image" src="https://user-images.githubusercontent.com/16933202/224662690-75b2c2e1-9d22-44d5-b7c4-1b0e8b024e9a.png">
