styles.css

body {
  background: #555;
  margin-top: 60px;
}

.stoplight-body {
  background: #f2b738;
  border-radius: 8px;
  border: 3px solid black;
  margin: 0 auto;
  max-width: 180px;
  height: 420px;
  display: flex;
  flex-direction: column;
  justify-content: space-around;
  align-items: center;
}

.stoplight-light {
  width: 100px;
  height: 100px;
  border-radius: 100%;
  position: relative;
  opacity: .3;
}

.stoplight-light::before {
  background: rgba(0, 0, 0, .6);
  display: block;
  width: 100px;
  height: 100px;
  content: '';
  border-radius: 100%;
  position: relative;
}

.stoplight-light.active::before {
  z-index: -1;
}

.stoplight-light.active {
  opacity: 1;
  border: 3px solid black;
}

.stoplight-go {
  background: #37ba18;
}

.stoplight-warning {
  background: #eadd15;
}

.stoplight-stop {
  background: #e11d1d;
}