/*Create Your Own Custom Circle Gradient Background PNG.  

Full Screen view is probably best so you can see full image. Only works in Chrome / Safari. 

A new circle gradient scheme is randomly generated with each click / touch of the canvas - if there's one you like, you can right click / touch-hold and save the PNG. 

You can also make the circles more defined, or even less defined (for a smooth gradient), by playing with the color stop values where noted in below JS
*/