原文地址：https://segmentfault.com/a/1190000014842868
简化版地址：https://scrimba.com/c/cgaZLh6
感想：笨蛋，想不出自己的东西。。。
HTML代码：
<!DOCTYPE HTML>
<html>
<head>
<link rel="stylesheet" href="index.css">
</head>
<body>
<div>
<h1>Who Am I</h1>
<p>
<span class="question">Who gives you milk?</span>
<span class="answer">cow</span>
</p>
<p>
<span class="question">Who likes to eat flies？</span>
<span class="answer">frog</span>
</p>
<p>
<span class="question">Who have large claws?</span>
<span class="answer">crab</span>
</p>
</div>
</body>
</html>
CSS代码：
html, body {
margin:;
padding:;
height: 100%;
display: flex;
justify-content: center;
align-items: center;
background-color: green;
color: gold;
text-align: center;
}
p {
width: 400px;
height: 2.5em;
font-size: 24px;
border: 2px solid gold;
line-height: 2.5em;
border-radius: 10px;
font-family: sans-serif;
letter-spacing: 2px;
word-spacing: 2px;
box-shadow: 5px 5px 10px rgba(0, 0, 0, 0.2);
position: relative;
/* 溢出隐藏 */
overflow: hidden;
}
p span {
/* 绝对定位,使两个span重合 */
position: absolute;
/* 占父元素全部 */
width: 100%;
top:;
left:;
/* 使之有动画效果 */
transition: 0.5s ease-out;
}
p .question,
p:hover .answer {
left:;
}
p:hover .question {
left: 100%;
}
p .answer {
color: whitesmoke;
font-size: 1.1em;
text-transform: uppercase;
background: rgba(0, 0, 0, 0.1);
left: -100%;
}