要同时设置 flex-direction和flex-wrap属性，请使用单个属性 flex-flow
您可以尝试运行以下代码来实现flex-flow属性，以设置flex的direction和wrap属性：
<!DOCTYPE html>
<html>
<head>
<style>
.mycontainer {
display: flex;
background-color: orange;
flex-flow: column wrap;
}
.mycontainer > div {
background-color: white;
text-align: center;
line-height: 40px;
font-size: 25px;
width: 100px;
margin: 5px;
}
</style>
</head>
<body>
<h1>Quiz</h1>
<div class = "mycontainer">
<div>Q1</div>
<div>Q2</div>
<div>Q3</div>
<div>Q4</div>
<div>Q5</div>
<div>Q6</div>
<div>Q7</div>
<div>Q8</div>
<div>Q9</div>
</div>
</body>
</html>