css3弹性盒模型flex快速入门与上手(align-content与align-items)

接着上文css3弹性盒模型flex快速入门与上手1继续，上文还剩下两个父容器的属性align-items和align-content.

一、align-content:多行的副轴对齐方式

含义	多行的副轴对齐方式
可选值	`stretch \| flex-start \| center \| flex-end \| space-between \| space-around`
默认值	`stretch`

属性定义了多根轴线的对齐方式。如果项目只有一根轴线，该属性不起作用

即：此属性只在flex容器中有多行flex元素时才有作用.

 1 <!DOCTYPE html>
 2 <html lang="en">
 3 
 4 <head>
 5     <meta charset="UTF-8">
 6     <meta name="viewport" content="width=device-width, initial-scale=1.0">
 7     <meta http-equiv="X-UA-Compatible" content="ie=edge">
 8     <title>flex布局 - by ghostwu</title>
 9     <style>
10         #box {
11             display: flex;
12             flex-direction: row;
13             flex-wrap: wrap;
14             align-content: flex-start;
15             /* align-content: flex-end; */
16             /* align-content: center; */
17             /* align-content: stretch; */
18             /* align-content: space-between; */
19             /* align-content: space-around; */
20             height: 400px;
21             background: #ccc;
22         }
23 
24         #box div {
25             width: 100px;
26             height: 100px;
27             background: #09f;
28             margin: 10px;
29         }
30     </style>
31 </head>
32 
33 <body>
34     <div id="box">
35         <div>1</div>
36         <div>2</div>
37         <div>3</div>
38         <div>4</div>
39         <div>5</div>
40         <div>6</div>
41         <div>7</div>
42         <div>8</div>
43         <div>9</div>
44         <div>10</div>
45         <div>11</div>
46         <div>12</div>
47         <div>13</div>
48         <div>14</div>
49     </div>
50 </body>
51 
52 </html>

flex-direction: row;

flex-wrap: wrap;

align-content: flex-start;

flex-direction: row;

flex-wrap: wrap;

align-content: flex-end;

flex-direction: row;

flex-wrap: wrap;

align-content: center;

flex-direction: row;

flex-wrap: wrap;

align-content: stretch;

设置了align-content为stretch时，把容器的子元素height变成auto,不要设置固定的高度，才能看见拉伸效果

#box div {

width: 100px;

height: auto;

background: #09f;

margin: 10px;

}

flex-direction: row;

flex-wrap: wrap;

align-content: space-between;

flex-direction: row;

flex-wrap: wrap;

align-content: space-around;

flex-direction: column;

flex-wrap: wrap;

align-content: space-around;

把flex-direction变成column方向.

小结：这个属性一定要有多行flex元素，否则看不到效果，即配合flex-wrap: wrap;让flex元素换行才能看见效果

align-items：单行的副轴对齐方式

含义	单行的副轴对齐方式
可选值	`flex-start \| flex-end \| center \| stretch \| baseline`
默认值	`stretch`

 1 <!DOCTYPE html>
 2 <html lang="en">
 3 <head>
 4     <meta charset="UTF-8">
 5     <meta name="viewport" content="width=device-width, initial-scale=1.0">
 6     <meta http-equiv="X-UA-Compatible" content="ie=edge">
 7     <title>flex布局 - by ghostwu</title>
 8     <style>
 9         #box {
10             display: flex;
11             /* flex-direction: column; */
12             flex-direction: row;
13             /* align-items: flex-start; */
14             align-items: flex-end;
15             /* align-items: center; */
16             /* align-items: baseline; */
17 
18             height:400px;
19             background:#ccc;
20         }
21         #box div {
22             width: 100px;
23             height: 100px;
24             background: #09f;
25             margin: 10px;
26             box-sizing: border-box;
27         }
28     </style>
29 </head>
30 <body>
31     <div id="box">
32         <div>1</div>
33         <div>2</div>
34         <div>3</div>
35         <div>4</div>
36         <div>5</div>
37         <div>6</div>
38         <div>7</div>
39         <div>8</div>
40         <div>9</div>
41     </div>
42 </body>
43 </html>