a {
    text-decoration: none;
    color: white;
}

body {
    font-family: sans-serif;
}

#controlPanel {
    float: left;
    padding-top: 30px;
}

.button {
    background-color: gray;
    color: white;
    border-radius: 10px;
    padding: 20px;
    text-align: center;
    margin: 90px 40px;
    cursor: pointer;
}

#traffic-light {
    height: 550px;
    width: 200px;
    float: left;
    background-color: #333;
    border-radius: 40px;
    margin: 30px 0;
    padding: 20px;
}

.bulb {
    height: 150px;
    width: 150px;
    background-color: #111;
    border-radius: 50%;
    margin: 25px auto;
    transition: background 500ms;
}

#goLight.active {
    background-color: green;
}

#stopLight.active {
    background-color: red;
}

#slowLight.active {
    background-color: orange;
}