flex

<pre>
<div class="parent">
<div class="item-1"></div>
<div class="item-2"></div>
<div class="item-3"></div>
</div>

<style type="text/css">
.parent {
display: flex;
width: 600px;
}
.parent > div {
height: 100px;
}
.item-1 {
width: 140px;
flex: 2 1 0%;
background: blue;
}
.item-2 {
width: 100px;
flex: 2 1 auto;
background: darkblue;
}
.item-3 {
flex: 1 1 200px;
background: lightblue;
}
</style>

</pre>

主轴上父容器总尺寸为 600px
子元素的总基准值是：0% + auto + 200px = 300px，其中

• 0% 即 0 宽度
• auto 对应取主尺寸即 100px
  故剩余空间为 600px - 300px = 300px
  伸缩放大系数之和为： 2 + 2 + 1 = 5
  剩余空间分配如下：
• item-1 和 item-2 各分配 2/5，各得 120px
• item-3 分配 1/5，得 60px
  各项目最终宽度为：
• item-1 = 0% + 120px = 120px
• item-2 = auto + 120px = 220px
• item-3 = 200px + 60px = 260px

<pre>
.item {flex: 2333 3222 234px;}
.item {
flex-grow: 2333;
flex-shrink: 3222;
flex-basis: 234px;
}

//
.item {flex: none;}
.item {
flex-grow: 0;
flex-shrink: 0;
flex-basis: auto;
}
//
.item {flex: auto;}
.item {
flex-grow: 1;
flex-shrink: 1;
flex-basis: auto;
}
//
.item {flex: 1;}
.item {
flex-grow: 1;
flex-shrink: 1;
flex-basis: 0%;
}
//
.item-1 {flex: 0%;}
.item-1 {
flex-grow: 1;
flex-shrink: 1;
flex-basis: 0%;
}
.item-2 {flex: 24px;}
.item-1 {
flex-grow: 1;
flex-shrink: 1;
flex-basis: 24px;
}
//
.item {flex: 2 3;}
.item {
flex-grow: 2;
flex-shrink: 3;
flex-basis: 0%;
}
//
.item {flex: 2333 3222px;}
.item {
flex-grow: 2333;
flex-shrink: 1;
flex-basis: 3222px;
}

</pre>
参考：
Flex 布局教程：语法篇
Flex 布局教程：实例篇