Use the flex-wrap property to set is the flex items wrap or not.
You can try to run the following code to implement the flex-wrap property. Here the flex items wrap
Example
<!DOCTYPE html>
<html>
<head>
<style>
.mycontainer {
display: flex;
background-color: orange;
flex-wrap: 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>