property defines how the speed will be calculated during the transition and allows for a transition to change speed over its duration.
The possible values are :
|starts slowly, and then goes fast and ends slowly|
|goes at the same speed from start to end|
|starts slowly and ends with a slight speed difference from the ease value|
|The cubicbezier timing function requires four numeric values to calculate the speed of your transition. In fact, all timing function values are defined by using a specific cubic-bezier curve, which is itself defined by four control points—for instance, the ease function is equivalent to cubic-bezier(0.25, 0.1, 0.25, 1.0).|
Read more about them at http://en.wikipedia.org/wiki/B%C3%A9zier_curve#Cubic_B.C3.A9zier_curves).