代码示例：（标识：css3_flexbox_align-content_space-around）
<!DOCTYPE html>
<html>
<head>
<style>
.flex-container {
display: flex;
height: 600px;
flex-wrap: wrap;
align-content: space-around;
background-color: DodgerBlue;
}
.flex-container > div {
background-color: #f1f1f1;
width: 100px;
margin: 10px;
text-align: center;
line-height: 75px;
font-size: 30px;
}
</style>
</head>
<body>
<h1>align-content 属性</h1>
<p>"align-content: space-around;" 显示弹性线在其之前、之间和之后带有空格：</p>
<div class="flex-container">
<div>1</div>
<div>2</div>
<div>3</div>
<div>4</div>
<div>5</div>
<div>6</div>
<div>7</div>
<div>8</div>
<div>9</div>
<div>10</div>
<div>11</div>
<div>12</div>
</div>
</body>
</html>
