flex 布局放在父级元素上的属性flex-direction右往左排默认向右flex-direction:row;左往

放在父级元素上的属性

flex-direction

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        .father{
            display: flex;
            width: 500px;
            height: 500px;
            border: 3px solid lightcoral;
              /* 默认向右 */
            flex-direction: row;
            /* flex-direction: row-reverse; */
        }
        .father div{
            width: 80px;
            height: 80px;
            background-color: skyblue;
            border: 2px solid springgreen;
          
        }
    </style>
</head>
<body>
    <div class="father">
        <div>首页</div>
        <div>分类</div>
        <div>购物车</div>
        <div>我的</div>
    </div>    
</body>
</html>

右往左排默认向右 flex-direction: row;

左往右排 flex-direction: row-reverse;

上往下排 flex-direction: column;

下往上排 flex-direction: column-reverse; 子盒子的顺序是改变的

justify-content

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        .father{
            display: flex;
            width: 500px;
            height: 500px;
            border: 3px solid lightcoral;
            flex-direction: row;
            justify-content: flex-start;
            /* justify-content: flex-end; */
        }
        .father div{
            width: 80px;
            height: 80px;
            background-color: skyblue;
            border: 2px solid springgreen;
          
        }
    </style>
</head>
<body>
    <div class="father">
        <div>首页</div>
        <div>分类</div>
        <div>购物车</div>
        <div>我的</div>
    </div>    
</body>
</html>

justify-content: flex-start;

justify-content: flex-end; 注意是子盒子是没有从右向左边排列的

水平居中（经常用到的） justify-content: center;
justify-content: space-around;

justify-content: space-between; 完成这种布局用到

两边贴边中间平均分配

justify-content 以y轴为主轴

flex-direction: column;

justify-content: flex-start;

justify-content: flex-end;

justify-content: center; （开发常用）

justify-content: space-around;

justify-content: space-between;

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        .father{
            display: flex;
            width: 500px;
            height: 500px;
            border: 3px solid lightcoral;
            flex-direction: row;
          
        }
        .father div{
            width: 80px;
            height: 80px;
            background-color: skyblue;
            border: 2px solid springgreen;
          
        }
    </style>
</head>
<body>
    <div class="father">
        <div>首页</div>
        <div>分类</div>
        <div>购物车</div>
        <div>发展</div>
        <div>项目</div>
        <div>我的</div>
        <div>笔芯</div>
    </div>    
</body>
</html>

flex布局中，默认的子元素是不换行的，如果装不下，会缩小子元素的宽度，放到父元素里面

默认是flex-wrap：nowrap

换行：flex-wrap：wrap

这也是我写页面那时候与到头疼的问题

align-items 设置侧轴的（适用于单行）

 flex-direction: row;
 justify-content: center;
 align-items: center;

 .father{
            display: flex;
            width: 500px;
            height: 500px;
            border: 3px solid lightcoral;
            /* flex-direction: row; */
            flex-direction: row;
           justify-content: center;
           /* align-items: center; */
           /* align-items:flex-start; */
           /* align-items:flex-end; */
           /* 伸缩 不要给子盒子设置高度 */
           align-items:stretch;
          
        }
        .father div{
            width: 80px;
            /* height: 80px; */
            background-color: skyblue;
            border: 2px solid springgreen;
          
        }

align-items:flex-start;

align-items:flex-end;

主轴是侧轴：

flex-direction: column;
justify-content: center;
align-items: center;

align-items:flex-start;

align-items:flex-end;

align-items:stretch; 不要给宽了

注意：

没有像水平justify-content 中的space-around 和space-between属性题外话：就像实现单行文本垂直居中用行高等于外层盒子高度就行但是对于多行文本是不行的

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        .father{
            height: 500px;
            width: 500px;
            background-color: bisque;
            border: 1px solid saddlebrown;
        }
        .father  p{
            color: lightgreen;
            font-size: 20px;
            line-height: 500px;
        }
    </style>
</head>
<body>
    <div class="father">
        
        <p>雷克萨斯全混动科技可支持前驱、后驱、四驱等所有驱动系统，并覆盖紧凑型轿车至中大型SUV等多款车型，让消费者有多种选择，从而带来不凡体验。</p>
      
    </div>
</body>
</html>

align-content (适用于多行)

ps：在单行里面设置align-content是无效的

常用布局案例：

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        ul{
            list-style: none;
            margin: 0;
            padding: 0;
        }
        .father{
            
            height: 450px;
            width: 900px;
            background-color: pink;
            display: flex;
            flex-direction: row;
            flex-wrap: wrap;
            justify-content: space-between;
            align-content: space-between;
        }
        li{
            width: 200px;
            height: 200px;
            background-color: gray;
        }
    </style>
</head>
<body>
    <ul class="father">
        <li>1</li>
        <li>2</li>
        <li>3</li>
        <li>4</li>
        <li>5</li>
        <li>6</li>
        <li>7</li>
        <li>8</li>
    </ul>
</body>
</html>

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        ul{
            list-style: none;
            margin: 0;
            padding: 0;
        }
        .father{
            
            height: 500px;
            width: 900px;
            background-color: pink;
            display: flex;
            flex-direction: row;
            flex-wrap: wrap;
           
            align-content: flex-start;
            /* align-content: flex-end; */
            /* align-content: stretch; */
            /* align-content: space-around; */
            /* justify-content: space-between; */
        }
        li{
            width: 200px;
            height: 200px;
            background-color: gray;
            border: 2px solid springgreen;
        }
    </style>
</head>
<body>
    <ul class="father">
        <li>1</li>
        <li>2</li>
        <li>3</li>
        <li>4</li>
        <li>5</li>
        <li>6</li>
        <li>7</li>
        <li>8</li>
    </ul>
</body>
</html>

align-content: flex-start;

align-content: flex-end;

把li的高度去掉/* height: 200px; */ align-content: stretch;

align-content: space-around;

align-content: space-between;

flex-flow

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        ul{
            list-style: none;
            margin: 0;
            padding: 0;
        }
        .father{
            
            height: 900px;
            width: 900px;
            background-color: pink;
            display: flex;
            flex-direction:column;
            flex-wrap: wrap;
        }
        li{
            width: 200px;
            height: 200px;
            background-color: gray;
            border: 2px solid green;
        }
    </style>
</head>
<body>
    <ul class="father">
        <li>1</li>
        <li>2</li>
        <li>3</li>
        <li>4</li>
        <li>5</li>
        <li>6</li>
        <li>7</li>
        <li>8</li>
    </ul>
</body>
</html>

/* flex-direction:column; flex-wrap: wrap; */

flex-flow: column wrap; 是上面的合并

flex布局子项常见属性

注意：flex是分配剩余空间的哦

案例:左右固定中间自适应

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        section{
            width:60%;
            height: 150px;
            background-color: pink;
            display: flex;
            margin: 0 auto;
        }
    
        section div:nth-child(1){
            width: 100px;
            height: 150px;
            background-color: green;
        }
        section div:nth-child(2){
            flex: 1;
            background-color: red;
        }
        section div:nth-child(3){
            width: 100px;
            height: 150px;
            background-color:blue ;
        }
    </style>
</head>
<body>
    
    <section>
        <div></div>
        <div></div>
        <div></div>
    </section>
</body>
</html>

父元素设置flex 子元素为两个块级元素宽加起来为100% 实现同一行显示

  .father{
            width: 500px;
            height: 200px;
            background-color: purple;

            display: flex;
        }
        .left{
            width: 30%;
            height: 80%;
            background-color: gray;
        }
        .right{
            width: 70%;
            height: 80%;
            background-color:yellow;
        }
        
        
    <div class="father">
        <div class="left"></div>
        <div class="right"></div>
    </div>

align-self

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        .father{
            width: 500px;
            height: 500px;
            background-color: #ccc;
            display: flex;
        }
        .father div{
            
            width: 100px;
            height: 100px;
            background-color: blue;
        }
        .father div:nth-child(3){

            width: 100px;
            height: 100px;
            background-color: blue;
            align-self: flex-end;
        }
    </style>
</head>
<body>
    <div class="father">
        <div>
            我的天呐
        </div>
        <div>
            我的天呐
        </div>
        <div>
            我的天呐
        </div>
    </div>
</body>
</html>

order 默认是0 越小越靠前

.father div:nth-child(2){
            order: -2;
            width: 100px;
            height: 100px;
            background-color: blue;
            align-self: center;
}

flex 布局