https://codepen.io/anon/pen/xEykRg?editors=1100 https://codepen.io/anon/pen/xEykRg?editors=1100 in retrospect probably not a complete solution in of itself, but

https://codepen.io/anon/pen/xEykRg?editors=1100 https://codepen.io/anon/pen/xEykRg?editors=1100 in retrospect probably not a complete solution in of itself, but if doing the top 3 borders, with a :after with a gradient background image, should work for all colors