el-row一行放置3个el-col，有时出现空行现象

利用el-row的type属性，将type设置为flex，启用flex布局，再设置justify和align属性，即可避免该问题出现。

<el-row type="flex" class="row-bg">
  <el-col :span="6"><div class="grid-content bg-purple"></div></el-col>
  <el-col :span="6"><div class="grid-content bg-purple-light"></div></el-col>
  <el-col :span="6"><div class="grid-content bg-purple"></div></el-col>
</el-row>
<el-row type="flex" class="row-bg" justify="center">
  <el-col :span="6"><div class="grid-content bg-purple"></div></el-col>
  <el-col :span="6"><div class="grid-content bg-purple-light"></div></el-col>
  <el-col :span="6"><div class="grid-content bg-purple"></div></el-col>
</el-row>
<el-row type="flex" class="row-bg" justify="end">
  <el-col :span="6"><div class="grid-content bg-purple"></div></el-col>
  <el-col :span="6"><div class="grid-content bg-purple-light"></div></el-col>
  <el-col :span="6"><div class="grid-content bg-purple"></div></el-col>
</el-row>
<el-row type="flex" class="row-bg" justify="space-between">
  <el-col :span="6"><div class="grid-content bg-purple"></div></el-col>
  <el-col :span="6"><div class="grid-content bg-purple-light"></div></el-col>
  <el-col :span="6"><div class="grid-content bg-purple"></div></el-col>
</el-row>
<el-row type="flex" class="row-bg" justify="space-around">
  <el-col :span="6"><div class="grid-content bg-purple"></div></el-col>
  <el-col :span="6"><div class="grid-content bg-purple-light"></div></el-col>
  <el-col :span="6"><div class="grid-content bg-purple"></div></el-col>
</el-row>