Transition Css Hover

/* Transition is how much my element will take time to change his state
or apply a specific style on it at specific */
.my-div{
background-color: #f00; /*Red*/
transition: 3s ease-in-out;
/* transition: .5s ease-in-out; [0.5 seconds] */
}
.my-div:hover{
background-color: #00f; /*Blue*/
}
/* .my-div background-color will be changed from red to blue in 3 seconds*/