SOURCE

<div class="blank-container">
  <div class="content">
    <div>
      123123
    </div>
    <div>
      123123
    </div>
    <div>
    </div>

.blank-container {
  /* position: absolute;
  top: 0;
  right: 0;
  left: 0;
  bottom: 0;
  margin: auto; */
  /* border: 1px solid blue; */
  width: 100%;
  height: 100%
}

.content {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
}