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console 命令行工具 X clear

                    
>
console
<div class="father">
  <div class="box first">
    一
  </div>
  <div class="box">
    二
  </div>
  <div class="box">
    三
  </div>
</div>
.box {
  background-color: gray;
  width: 100px;
  height: 30px;
  margin: 10px 10px;
}

.first {
  float: left;
}

.father {
  width: 300px;
  border-style: solid; 
  border-width: 2px;
}