例如，css align-content 属性不适用于块容器
<html>
<body>
<div class="container">
<div class="item">this is item</div>
</div>
</body>
</html>
css代码
.container{
background-color:yellow;
width:350px;
height:200px;
align-content:center;
}
.item{
width:100px;
background-color:gray;
}
css框对齐模块说明截图
【问题讨论】：
没有display: flex、align-items 和justify-content 将无法工作。
.container{
background-color:yellow;
width:350px;
height:200px;
display: flex; /* without display: flex, align-items and justify-content wont' work */
align-items: center; /* to vertically center the content */
justify-content: center; /* to horizontally center the content */
}
.item{
width:100px;
background-color:gray;
}<div class="container">
<div class="item">this is item</div>
</div>【讨论】：