squares.css

html, body {
  padding: 0;
  margin: 0;
  background-color: #25275a;
  width: 100%;
  height: 100%;
}
.box {
  width: 50px;
  height: 150px;
}
.boxes {
  display: flex;
  align-items: center;
  justify-content: center;
  height: 100%;
}
.boxes__inner {
  display: flex;
  overflow: hidden;
  height: 165px;
}