html {
  font-family: sans-serif;
}

h1 {
  text-align: center;
}

.container {
  display: flex;
  flex-wrap: wrap;
}

.center {
  margin: auto;
  max-width: 500px;
}

.color {
  display: block;
  width: calc(100vw - 24px);
  height: 100px;
  border: 1px solid black;
  box-sizing: border-box;
  text-align: center;
  line-height: 100px;
  font-size: 18px;
  font-weight: bold;
  cursor: pointer;
  margin-bottom: 16px;
  border-radius: 12px;
}

.red {
  background-color: #f00;
}

.green {
  background-color: #0f0;
}

.blue {
  background-color: #00f;
  color: #fff;
}

.cyan {
  background-color: #0ff;
}

.yellow {
  background-color: #ff0;
}

.orange {
  background-color: #ff8000;
}

.purple {
  background-color: #f0f;
}

.white {
  background-color: #fff;
}

.black {
  background-color: #000;
  color: #fff;
}