*{
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body{
    display: flex;
    justify-content: center;
    align-items: center; 
    min-height: 100vh;
    background: #222; 
}

body.on{
   background: radial-gradient(#555,#111); 
}

.wire{
    position: absolute;
    left: calc(50% - 2px);
    bottom: 50%;
    height: 60vh;
    width: 4px;
    background: #000;
    z-index: 1;
}

.bulb{
    position: relative;
    width: 80px;
    height: 80px;
    background: transparent;
    z-index: 2;
}

.bulb i {
    font-size: 4rem;
    color: #444;
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%,-50%) rotate(180deg);
}

.switch{
    position: absolute;
    top: 60px;
    right: 100px;
    width: 40px;
    height: 40px;
    background: #ccc;
    border-radius: 50%;
    display: flex;
    justify-content: center;
    align-items: center;
    box-shadow: gray 0px 10px 15px -5px;
    cursor: pointer;
}

.switch i{
    font-size: 1.5rem;
}

.on .bulb i {
    color: #ffd700;
}

.on .switch{
    background: #4caf50;
}