how to animate element from top to bottom in css code example

Example: css top to bottom animation

//html code
<div id="topToBottom"></div>

//css code
#topToBottom {
  animation: topToBottom ease 2s;
  -webkit-animation: topToBottom ease 2s;
  -moz-animation: topToBottom ease 2s;
  -o-animation: topToBottom ease 2s;
  -ms-animation: topToBottom ease 2s;
}
@keyframes topToBottom {
  0% {
    margin-top: -23%;
  }
  100% {
    margin-top: 0%;
  }
}

@-moz-keyframes topToBottom {
  0% {
    margin-top: -23%;
  }
  100% {
    margin-top: 0%;
  }
}

@-webkit-keyframes topToBottom {
  0% {
    margin-top: -23%;
  }
  100% {
    margin-top: 0%;
  }
}

@-o-keyframes topToBottom {
  0% {
    margin-top: -23%;
  }
  100% {
    margin-top: 0%;
  }
}

@-ms-keyframes topToBottom {
  0% {
    margin-top: -23%;
  }
  100% {
    margin-top: 0%;
  }
}