flex布局两端对齐，最后一行左对齐

原先效果

<div class="flex-container">
  <div class="item">仓库失火烧毁大量老坛酸菜牛肉面1div>
  <div class="item">仓库失火烧毁大量老坛酸菜牛肉面2div>
  <div class="item">仓库失火烧毁大量老坛酸菜牛肉面3div>
  <div class="item">仓库失火烧毁大量老坛酸菜牛肉面4div>
  <div class="item">仓库失火烧毁大量老坛酸菜牛肉面5div>
div>

.flex-container {
  padding-top: 20px;
  display: flex;
  justify-content: space-between;
  flex-wrap: wrap;
  .item {
    width: 120px;
    background: pink;
    flex-shrink: 0;
    margin-bottom: 10px;
    padding: 6px;
    box-sizing: border-box;
  }
}

实现最后一行左对齐，只需要给父元素加上一个伪类元素，宽度同子元素的宽度即可

 .flex-container:after {
    content: "";
    width: 120px;
  }

最终效果如下