<div class="box">
    <p>I am not empty</p>
  </div>
  <div class="other-box">
    <p>I am also not empty</p>
  </div>

.body {
  background: #fff;
}

.box {
  margin-bottom: -30px;
  height: 100px;
  border: 2px solid #000;
}
.other-box {
  margin-top: -15px;
  height: 100px;
  border: 2px solid red;
}