Need help with D3 gradient

I have been working on a d3 project of my own for fun (here’s the link to it Everything’s working fine but after you enter a date and start the timer, the gradient looks some what odd since it is a linear gradient. I tried to use radial gradient but that just made it look worse. Is there a way to make a gradient go around the circle and make something like this:
instead of something like this:

(Which is what is happening in my code)
Is there maybe another type of gradient in d3 that could solve this?