要使用CSS在 flex-grow 属性上实现动画，您可以尝试运行以下代码
<!DOCTYPE html>
<html>
<head>
<style>
.mycontainer {
display: flex;
background-color: red;
align-content: space-between;
}
.mycontainer > div {
background-color: white;
text-align: center;
line-height: 40px;
font-size: 25px;
width: 100px;
margin: 5px;
}
div {
animation: myanim 4s infinite;
}
@-webkit-keyframes myanim {
30% {
flex-grow: 3;
}
}
</style>
</head>
<body>
<h1>Quiz</h1>
<div class = "mycontainer">
<div style = "flex-grow: 1">A1</div>
<div style = "flex-grow: 1">A2</div>
<div style = "flex-grow: 20">A3</div>
<div style = "flex-grow: 1">A4</div>
<div style = "flex-grow: 1">A5</div>
</div>
</body>
</html>