html, body {
  padding: 0;
  margin: 0;
  background: wheat;
  font-family: 'Press Start 2P', cursive;
}
html #app, body #app {
  display: flex;
  justify-content: center;
  align-items: center;
  height: 100vh;
}
html #app #traffic_light, body #app #traffic_light {
  padding: 15px;
  border: 1px solid;
  display: flex;
  justify-content: center;
  align-items: center;
  background: rgba(0, 0, 0, 0.9);
  border-radius: 15px;
  border: 4px solid gray;
}
html #app #traffic_light .light, body #app #traffic_light .light {
  margin: 0 5px;
  border: 4px solid gray;
  border-radius: 50%;
  width: 60px;
  height: 60px;
  backgroud: black;
}
html #app #traffic_light .light.red_light, body #app #traffic_light .light.red_light {
  background: red;
}
html #app #traffic_light .light.yellow_light, body #app #traffic_light .light.yellow_light {
  background: yellow;
  color: white;
  display: flex;
  justify-content: center;
  align-items: center;
  font-size: 1.5rem;
}
html #app #traffic_light .light.yellow_light .counting_sec, body #app #traffic_light .light.yellow_light .counting_sec {
  margin-left: 3px;
  margin-top: 4px;
}
html #app #traffic_light .light.green_light, body #app #traffic_light .light.green_light {
  background: green;
}