html, body {
  width: 100%;
  height:100%;
  overflow: hidden;
}

body {
    background: linear-gradient(-45deg, #000000, #de0000, #ffcf00);
    background-size: 400% 400%;
    animation: gradient 15s ease infinite;
}

@keyframes gradient {
    0% {
        background-position: 0% 50%;
    }
    50% {
        background-position: 100% 50%;
    }
    100% {
        background-position: 0% 50%;
    }
}


.mute-video {
    background:url(http://cdn.flaticon.com/png/64/60750.png) no-repeat center;
    background-size:32px;
    border:0;
    width:32px;
    height:32px;
    text-indent:-999px;
}
.unmute-video {
    background:url(http://cdn.flaticon.com/png/64/498.png) no-repeat center;
    background-size:32px;
}