...you can use this value to indicate you want to use the value of color for other properties that accept a color value: borders, box shadows, outlines, or backgrounds. This value was first supported by Opera in 2009, since then, Firefox 3.5+, Chrome 1+, and Safari 4+.
參考連結:
- css-tricks: http://css-tricks.com/currentcolor/
- Support ie9+: http://css-tricks.com/currentcolor/