*{
    margin: 0;
    padding: 0;
}
body{
    height: 100vh;
    display: flex;
    justify-content: center;
    align-items: center;
    background-color: #222;
}
.interruptor{
    width: 100px;
    height: 100px;
    border-radius: 50%;
    background-image: linear-gradient(to right,#ddd,#444);
    padding: 10px;
}
.interruptor span{
    display: block;
    height: 100px;
    border-radius: 50%;
    background-image: linear-gradient(to right,#222,#777);

}

.encendido span{
    background-image: linear-gradient(to right,#ff0,#f90);
    animation:efecto 0.4s infinite;

}


@keyframes efecto{
    0%,100%{
        box-shadow:0 0 5px 0 rgba(255, 255, 255,0);
    }
    50%{
        box-shadow:0 0 20px 10px rgba(255, 255, 255,0.4);

    }
}