You will need to use SVG to do this which is not widely supported yet. So basically you will need to use images.
you can use Open-jACOB Draw2D
Create a square with css then round the corners to the point that it eventually becomes a circle. This way is all made with code and it's more widely supported than trying to use a png.
Once you have the circles (whether plots or images), yes. They can even be animated.