用一条线连接两个div

<div id="div1"></div>
<div id="div2"></div>

#div1, #div2 {
  border-style: solid;
}

#div1, #div2 {
  border-style: solid;
  border-color: black;
  border-width: 1px;
}

#div1 {
  position: absolute;
  top: 50px;
  left: 50px;
  width: 100px;
  height: 100px;
}

#div2 {
  position: absolute;
  top: 50px;
  left: 200px;
  width: 100px;
  height: 100px;
}