正方形与flexbox的正方形

我正在尝试使用flexbox重新创建以下布局:

我几乎有布局明智,但我得到一些奇怪的flex-wrap行为,如下所示:

我的css如下:

.parent {
    display: flex;
    justify-content: space-between;
    .square-container {
      width: calc(33% - 1.333px);
      display: flex;
      flex-wrap: wrap;
      justify-content: space-between;

    &:before {
      content:'';
      float:left;
      padding-top:100%;
      }

      .small-square {
          width: calc(50% - 2px);
          height: calc(50% - 2px);
          background: red;
          flex-shrink: 0;
      }     
    }
}

html如下:

我觉得我在这里错过了一些重要的flexbox属性.谢谢您的帮助!

你可以很容易地做到:

.flex {
  display: flex;
  flex-direction: column;
  flex-wrap: wrap;
  height: 210px;
  justify-content: space-between;
  width: 650px;
}

.small {
  width: 100px;
  height: 100px;
  background: red;
}

.large {
  width: 210px;
  height: 210px;
  background: red;
}