CSS3新属性之---flex box布局实例

flex box布局实例

flex的强大之处在于不管什么布局，几行命令即可实现

/*本节模板div元素（代表骰子的一个面）是Flex容器，span元素（代表一个点）是Flex项目。如果有多个项目，就要添加多个span元素，以此类推。*/
<div class="box">
<span class="item"></span>
</div>

骰子布局

单项目

.box {
display: flex;/*默认左上*/
justify-content: center;/*设置居中*/
justify-content: flex-end;/*设置右上*/
}
.box {
display: flex;
justify-content: center;/*+设置居中*/
align-items: center;/*垂直移动主轴*/
justify-content: flex-end;/*垂直移动右齐*/
align-items: flex-end;/*||垂直移动主轴*/
}

双项目

.box {
display: flex;
flex-direction: column;/*+竖直*/
justify-content: space-between;
align-items: center;/*+居中*/
align-items: flex-end;/*||居右*/
}
/*倾斜*/
.box {
display: flex;
}
.item:nth-child(2) {
align-self: center;
}
.box {
display: flex;
justify-content: space-between;
}
.item:nth-child(2) {
align-self: flex-end;
}

三项目

.box {
display: flex;
}

.item:nth-child(2) {
align-self: center;
}

.item:nth-child(3) {
align-self: flex-end;
}

##四项目

<div class="box">
<div class="column">
<span class="item"></span>
<span class="item"></span>
</div>
<div class="column">
<span class="item"></span>
<span class="item"></span>
</div>
</div>
.box {
display: flex;
flex-wrap: wrap;
align-content: space-between;
}

.column {
flex-basis: 100%;
display: flex;
justify-content: space-between;
}

##六项目

.box {
display: flex;
flex-wrap: wrap;
align-content: space-between;
}
.box {
display: flex;
flex-direction: column;
flex-wrap: wrap;
align-content: space-between;
}

##九项目

.box {
display: flex;
flex-wrap: wrap;
}

---
## 二，网格布局
### 1.基本网格（类似bootstrap实现）

<div class="Grid">
<div class="Grid-cell">...</div>
<div class="Grid-cell">...</div>
<div class="Grid-cell">...</div>
</div>
.Grid {
display: flex;
}

.Grid-cell {
flex: 1;
}

###2.百分比布局---某个网格的宽度为固定的百分比，其余网格平均分配剩余的空间。

.Grid {
display: flex;
}

.Grid-cell {
flex: 1;
}

.Grid-cell.u-full {
flex: 0 0 100%;
}

.Grid-cell.u-1of2 {
flex: 0 0 50%;
}

.Grid-cell.u-1of3 {
flex: 0 0 33.3333%;
}

.Grid-cell.u-1of4 {
flex: 0 0 25%;
}

### 3.圣杯布局---（Holy Grail Layout）一种最常见的网站布局

<body class="HolyGrail">
<header>...</header>
<div class="HolyGrail-body">
<main class="HolyGrail-content">...</main>
<nav class="HolyGrail-nav">...</nav>
<aside class="HolyGrail-ads">...</aside>
</div>
<footer>...</footer>
</body>
/适应小屏幕/
@media (max- 768px) {
.HolyGrail-body {
flex-direction: column;
flex: 1;
}
.HolyGrail-nav,
.HolyGrail-ads,
.HolyGrail-content {
flex: auto;
}
}
.HolyGrail {
display: flex;
min-height: 100vh;
flex-direction: column;
}

header,
footer {
flex: 1;
}

.HolyGrail-body {
display: flex;
flex: 1;
}

.HolyGrail-content {
flex: 1;
}

.HolyGrail-nav, .HolyGrail-ads {
/ 两个边栏的宽度设为12em /
flex: 0 0 12em;
}

.HolyGrail-nav {
/ 导航放到最左边 /
order: -1;
}

### 4.输入框布局---前提示后按钮

<div class="InputAddOn">
<span class="InputAddOn-item">...</span>
<input class="InputAddOn-field">
<button class="InputAddOn-item">...</button>
</div>
.InputAddOn {
display: flex;
}
.InputAddOn-field {
flex: 1;
}

### 5.悬挂布局---主栏的左侧或右侧，需要添加一个图片栏

<div class="Media">
<img class="Media-figure" src="" alt="">
<p class="Media-body">...</p>
</div>
.Media {
display: flex;
align-items: flex-start;
}

.Media-figure {
margin-right: 1em;
}
.Media-figure {
margin-right: 1em;
}

.Media-body {
flex: 1;
}

###6. 固定低栏

<body class="Site">
<header>...</header>
<main class="Site-content">...</main>
<footer>...</footer>
</body>
.Site {
display: flex;
min-height: 100vh;
flex-direction: column;
}
.Site-content {
flex: 1;
}

###7. 流式布局---列数固定自动分行

.parent {
200px;
height: 150px;

display: flex;
flex-flow: row wrap;
align-content: flex-start;
}

.child {
box-sizing: border-box;
background-color: white;
flex: 0 0 25%;
height: 50px;
border: 1px solid red;
}