Comment by TekMol

    CSS now has enough Math functions supported,
    particularly mod(), round(), and trigonometric
    functions

    CSS can not start a timer like JavaScript does,
    but nowadays it's possible to define a custom
    variable with the CSS Houdini API to track time
    in milliseconds. 

Why do we need all this when we have JavaScript?

Shouldn't the drawing layer be concerned with drawing primitives? Why put more and more of the higher layers into it?