新建html页面，复制下面内容，即可见效果
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>demo</title>
<style>
#box{
display: flex;
justify-content: center;
height: 100px;
border: 1px solid #eee;
align-items: center;
}
.container{
display: flex;
justify-content: space-around;
margin: 50px 0;
}
.item{
display: block;
30px;
height: 30px;
border:1px solid #eee;
background: #666;
border-radius: 50%;
}
section>div{
120px;
height: 120px;
border:1px solid #333;
border-radius: 20px;
padding: 10px;
}
/****************************************/
.one{
display: flex;
justify-content: center;
align-items: center;
}
.two{
display: flex;
justify-content: space-between;
}
.two .item:nth-of-type(2){
align-self: flex-end;
}
.three{
display: flex;
justify-content: space-between;
}
.three .item:nth-of-type(2){
align-self: center;
}
.three .item:nth-of-type(3){
align-self: flex-end;
}
.four{
display: flex;
justify-content: space-between;
}
.four .clumn{
display: flex;
flex-direction: column;
justify-content: space-between;
}
.five{
display: flex;
justify-content: space-between;
}
.five .clumn{
display: flex;
flex-direction: column;
justify-content: space-between;
}
.five .clumn:nth-of-type(2){
align-self: center;
}
.six{
display: flex;
justify-content: space-between;
}
.six .clumn{
display: flex;
flex-direction: column;
justify-content: space-between;
}
.seven{
display: flex;
flex-direction: column;
justify-content: space-between;
}
.seven .clumn:nth-of-type(1){
display: flex;
justify-content: space-between;
}
.seven .clumn:nth-of-type(2){
display: flex;
justify-content: flex-end;
}
</style>
</head>
<body>
<head>
<div id="box">
<span>display:flex的用法-demo</span>
</div>
</head>
<section class="container">
<div class="one">
<span class="item"></span>
</div>
<div class="two">
<span class="item"></span>
<span class="item"></span>
</div>
<div class="three">
<span class="item"></span>
<span class="item"></span>
<span class="item"></span>
</div>
<div class="four">
<div class="clumn">
<span class="item"></span>
<span class="item"></span>
</div>
<div class="clumn">
<span class="item"></span>
<span class="item"></span>
</div>
</div>
<div class="five">
<div class="clumn">
<span class="item"></span>
<span class="item"></span>
</div>
<div class="clumn">
<span class="item"></span>
</div>
<div class="clumn">
<span class="item"></span>
<span class="item"></span>
</div>
</div>
<div class="six">
<div class="clumn">
<span class="item"></span>
<span class="item"></span>
<span class="item"></span>
</div>
<div class="clumn">
<span class="item"></span>
<span class="item"></span>
<span class="item"></span>
</div>
</div>
<div class="seven">
<div class="clumn">
<span class="item"></span>
<span class="item"></span>
<span class="item"></span>
</div>
<div class="clumn">
<span class="item"></span>
</div>
</div>
</section>
</body>
</html>