<!DOCTYPE html>
<html lang="en-US">
<head>
<title>test of border-image-source: linear-gradient with border-image-slice</title>
<style>
div {
  border: 30px solid black;
  border-image: linear-gradient(to bottom right, red, blue);
  width: 180px;
  height: 180px;
}
div.border12 {
  border-image-slice: 12 12;
}
div.border30 {
  border-image-slice: 30 30;
}
div.border60 {
  border-image-slice: 60 60;
}
</style>
</head>
<body>
<div class="border12"></div>
<div class="border30"></div>
<div class="border60"></div>
</body>
</html>