You should specify two things to create CSS transition.
Let's take an example which defines transition effect on width property and duration of 3 seconds.
Note: If you don't specify the duration part, the transition will have no effect because its default value is 0. The transition effect is started when you move cursor over an element.
Note: The transition property is not supported by IE9 and earlier version.Test it Now
Note: When you take mouse cursor out of the element, it gains its original style gradually.
CSS Multiple Transition Effect
It is used to add transition effect for more than one CSS property. If you want to add transition effect on more than one property, separate those properties with a comma.
Let's take an example. Here, the transition effects on width, height and transformation.Test it Now