[Feature Request] Inconsistency between background and border on the same element

# Feature Request

## Is this feature request related to a problem?
Some inline text elements use `background-color` and `border-color`/`outline-color` at the same time to generate a larger color box. Dark Reader should generate identical color for them under dark mode.

## Screenshots
One usage on [Wikipedia](https://en.wikipedia.org/wiki/Template:Rail_color_box):

## Additional Context
I understand that there are performance concerns for keeping such consistency if those properties are defined separately for a element, so I'm proposing this only for properties defined in the same scope (both inline style, or defined in the same CSS rule).