[css] Gradient borders

There is a nice css tricks article about this here: https://css-tricks.com/gradient-borders-in-css/

I was able to come up with a pretty simple, single element, solution to this using multiple backgrounds and the background-origin property.

.wrapper {
  background: linear-gradient(#222, #222), 
              linear-gradient(to right, red, purple);
  background-origin: padding-box, border-box;
  background-repeat: no-repeat; /* this is important */
  border: 5px solid transparent;
}

The nice things about this approach are:

  1. It isn’t affected by z-index
  2. It can scale easily by just changing the width of the transparent border

Check it out: https://codepen.io/AlexOverbeck/pen/axGQyv?editors=1100