animation-timing-function

Defines an acceleration curve for each keyframe in a single animation.

animation-timing-function: <value>;

where <value> can be one of the following keywords:

• step-start: The easing curve for an animation that starts quickly and decelerates.
• step-end: The easing curve for an animation that starts slowly and decelerates.
• linear: The easing curve for an animation that starts and ends at the same speed.
• ease: The easing curve for an animation that starts and ends at the same speed.
• ease-in: The easing curve for an animation that starts slowly and accelerates.
• ease-out: The easing curve for an animation that starts slowly and decelerates.
• ease-in-out: The easing curve for an animation that starts and ends at the same speed.
• cubic-bezier(): The easing curve for an animation that starts and ends at the same speed.

Note: Applied property by property from keyframe to keyframe.

Apply ease-in-out to the animation-timing-function property of the div element:

div {
  height: 200px;
  width: 200px;
  background-color: blue;
  animation-name: slideright;
  animation-duration: 4s;
  animation-timing-function: ease-in-out;
}

@keyframes slideright {
  0% {
    margin-left: 0%;
  }
  50% {
    margin-left: 50%;
  }
  100% {
    margin-left: 100%;
  }
}