allow to set border for checkbox even if checkbox is checked

[Freundschaft]

right now its not possible to theme a checkbox like this:

which is as far as I can see due to this line of code

https://github.com/uber/baseweb/blob/7ebcc1c740a1db8f1ada94a734561f156dc6b8dd/src/checkbox/styled-components.js#L28

it would be nice if we could set an option somehow to enable borders even when the checkbox is checked.

[karanisverma]

@chasestarr I would like to work on this too :)

[tap0212]

@Freundschaft apparently you can achieve that. I was trying to solve this issue and got this =>