<div class="box-container">
  <div class="box red-box">Box 1</div>
  <div class="box green-box">Box 2</div>
  <div class="box blue-box">Box 3</div>
</div>
<div class="box-container">
  <div class="box blue-box">Box 4</div>
  <div class="box green-box">Box 5</div>
  <div class="box red-box">Box 6</div>
</div>

:root {
  --maroon-red: #800000;
  --dark-green: #013220;
  --navy-blue: #000080;
  --white: #fff;
}

.box-container {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-around;
}

.box {
  width: 200px;
  height: 100px;
  margin: 10px 0;
  display: flex;
  justify-content: center;
  align-items: center;
  font-size: 1.2rem;
  color: var(--white);
}

.red-box {
  background-color: var(--maroon-red);
}

.green-box {
  background-color: var(--dark-green);
}

.blue-box {
  background-color: var(--navy-blue);
}