Default Knob on mobile device looks very "blurry" or "aliased"(the circles are all blurred out)

Community General Discussion
1

Any way to improve the blurry image of the default knobs?

2

Does appending ?hdpi=1 to the server's url improve the situation ?

3

yes indeed! it's less blurry now, but still a little bit aliased when zoom in(quite acceptable).
thank you so much!