SOURCE

function HeadSlider(){
  $("#HeadSlider").show();
}

<div id="HeadSlider" class="fadeInDown">
  <h1>请问大所多  <h1>请问大所多</h1>
  <h1>请问大所多</h1>
  <h1>请问大所多</h1>
</h1>
</div>

<button type="button" onclick="HeadSlider()">下拉</button>

#HeadSlider{
  position:fixed;
  top:0;
  left:0;
  right:0;
  height:auto;
  background-color:gray;
  display:none;
  -webkit-animation-duration: 0.3s;
  animation-duration: 0.3s;
}