animation-timing-function: ease; /*increase speed toward middle then slow to end */
animation-timing-function: ease-in;/*start slow increase speed till end*/
animation-timing-function: ease-out;/*start quick decrease speed till end*/
animation-timing-function: ease-in-out;/*start slow, speeding up, decrease speed till end*/
animation-timing-function: linear;/*animates at an even speed.*/