style.css

@-webkit-keyframes flash {
    0% {
        opacity:1;
    }

    100% {
        opacity: 0;
    }
}
@-moz-keyframes flash {
    0% {
        opacity:1;
    }

    100% {
        opacity: 0;
    }
}



.flash {
    -webkit-animation-delay: 0;
    -mmoz-animation-delay: 0;
    -webkit-animation-duration: 0.8s;
    -moz-animation-duration: 0.8s;
    -webkit-animation-name: flash;
    -moz-animation-name: flash;
    -webkit-animation-fill-mode: forwards; /* this prevents the animation from restarting! */
    -moz-animation-fill-mode: forwards; /* this prevents the animation from restarting! */
}

html {
    background: black;
}

.controls {
    background: rgb(33, 33, 33);
    padding: 5px;
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 23px;
}

.setup, .range {
    display: inline;
    color: rgb(179, 179, 179);
    padding: 0 10px;
}

label, button {
    padding-right: 4px;
    vertical-align: middle;
}

input[type=number] {
    width: 40px;
    text-align: right;
}

input {
    vertical-align: middle;
    margin-right: 10px;
}

.bugs {
    position: absolute;
    top: 33px;
    left: 0;
    bottom: 0px;
    width: 100%;
}

.bug-wrapper {
    display: inline-block;

}

.bug {
    width: 100%;
    height: 100%;
    opacity: 0;
    background-image: radial-gradient(circle,rgba(102, 242, 31, 1) 0%, rgba(102, 242, 31, 0.5) 19%, rgba(0, 0, 0, 0) 40%);
}