當時的目的是想用純css實現一種鼠標hover A節點的時候B淡入，移出A的時候B淡出的功能，希望B在不顯示的時候不會占位且無事件（通常用display：none實現），於是就出現了困難。
以下是dom結構
<div id="container"></div>
<div id="detail"></div>
transition不支持display屬性的改變，而瀏覽器會將節點屬性的變化同display一起顯示，從而導致動畫效果的失效
#container{width:100px;
height:100px;
background-color: red;
display:block;
}
#container + #detail{
width:10px;
height:10px;
position:absolute;
background-color:#666;
top:15px;
left:15px;
opacity:0;
transition:all 0.4s;
display: none;
}
#container:hover + #detail,#detail:hover{
opacity:1;
display: block;
}
淡入完成了，淡出卻不行，這是因為detail節點不占位了
#container{width:100px;
height:100px;
background-color: red;
display:block;
}
#container + #detail{
width:10px;
height:10px;
position:absolute;
background-color:#666;
top:15px;
left:15px;
opacity:0;
-webkit-animation:hide 0.4s ease-out;
display: none;
}
#container:hover + #detail,#detail:hover{
opacity:1;
display: block;
-webkit-animation:show 0.4s ease-in;
transition-delay: 0s;
}
@-webkit-keyframes show /* Safari 和 Chrome */
{
0% {opacity:0;}
100% {opacity:1;}
}
@-webkit-keyframes hide /* Safari 和 Chrome */
{
0% {opacity:1;}
100% {opacity:0;}
}
最終實現代碼（只寫了chrome下的）
#container{width:100px;
height:100px;
background-color: red;
display:block;
}
#detail{
width:10px;
height:0px;
position:absolute;
background-color:#666;
top:15px;
left:15px;
opacity:0;
-webkit-animation:hide 0.4s ease-out;
display: block;
transition:height 1ms;
transition-delay: 0.4s;
overflow:hidden;
}
#container:hover + #detail{
height:10px;
opacity:1;
display: block;
-webkit-animation:show 0.4s ease-in;
transition-delay: 0s;
}
#detail:hover{
height:10px;
opacity:1;
display: block;
-webkit-animation:show 0.4s ease-in;
transition-delay: 0s;
}
@-webkit-keyframes show
{
0% {opacity:0;}
100% {opacity:1;}
}
@-webkit-keyframes hide
{
0% {opacity:1;}
100% {opacity:0;}
}