弹出菜单（鼠标移入父元素时子元素显示）

鼠标移入前

鼠标移入时显示的效果，

<div class="parent">
  <div class="child">
    移入显示我
  </div>
</div>

.parent {
  position: relative;
  width:100px;
  height:100px;
  background:blue;
}
.child {
  position: absolute;
  left:0;
  top:0;
  visibility: hidden;
  padding:5px;
  background:pink;
  border:1px solid #ccc;
}
.parent:hover > .child {
  visibility: visible;
}