css flex 子元素flex属性

css flex 子元素flex属性是flex-grow, flex-shrink 和 flex-basis的简写方式，默认值为0 1 auto，后两个属性可选。

#boxs
  {
        width:60%;
        height:100px;
        border:1px solid #333;
        display:flex;
  }
#boxs div
  {
        width:60%; 
        flex-grow:0;
        flex-shrink:1;
        flex-basis:1000px;
  }
 等同于
 #boxs
  {
        width:60%;
        height:100px;
        border:1px solid #333;
        display:flex;
  }
  #boxs div
  {
        width:60%; 
        flex:0 1 1000px; 
  }