To create a circle with radial gradient, you can try to run the following code. Set another parameter in radial gradient for shapes like circle
Example
<!DOCTYPE html> <html> <head> <style> #demo { height: 400px; background: radial-gradient(circle, red , blue, yellow); } </style> </head> <body> <h2>Radial Gradient</h2> <div id = "demo">Radial Gradients</div><br> </body> </html>