<!DOCTYPE html> <html lang="en-US"> <head> <title>test of border-image-source: radial-gradient</title> <style> div.border { border: 30px solid black; border-image: radial-gradient(ellipse 100% 50% at 50% 50%, blue 0%, red 100%); width: 180px; height: 180px; } </style> </head> <body> <div class="border"></div> </body> </html>