Here is the brief explanation on how to specify the duration of transition effect in CSS3.
transition-duration: time|initial|inherit; Where, time - Specifies how many seconds or milliseconds a transition effect takes to complete. Default value is 0s, means there will be no effect. initial - Sets this property to its default value. inherit - Inherits this property from its parent element.
The transition-duration property specifies how many seconds (s) or milliseconds (ms) a transition effect takes to complete.