body{
    margin:0;
    width:100%;
    height:100vh;
  }
  .draw-area{
    box-sizing: border-box;
    border:3px solid black;
    width:100%;
    height:100%;
  }
  .box{
    position: absolute;
    border:1px solid black;
    display: inline-block;
    background-color: red;
  }