Dimensions and Units

<div class="container">
  <div class="column left-column">
    <div class="box">Left Box 1</div>
    <div class="box">Left Box 2</div>
  </div>
  <div class="column right-column">
    <div class="box">Right Box 1</div>
    <div class="box">Right Box 2</div>
  </div>
</div>

.container {
  display: flex;
  justify-content: center;
  align-items: center;
  height: 100vh;
}
.column {
  width: 50%;
  height: 100%;
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
}
.left-column {
  background-color: #3498db;
}
.right-column {
  background-color: #2ecc71;
}
.box {
  width: 80%;
  margin: 10px;
  background-color: white;
}


.container {
  display: flex;
  justify-content: center;
  align-items: center;
  height: 100vh;
}
.column {
  width: 50%;
  height: 100%;
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
}
.left-column {
  background-color: #3498db;
}
.right-column {
  background-color: #2ecc71;
}
.box {
  width: 80%;
  height: 60px;
  margin: 10px;
  background-color: white;
}
