body {
  font-size: 15px;
}
.led {
  font-size: 1em;
  box-sizing: border-box;
  border: 1px solid rgba(0, 0, 0, 0.75);
  margin: 0;
  position: relative;
  display: inline-block;
  width: 1em;
  height: 1em;
  background: #808080;
  border-radius: 50%;
  vertical-align: text-bottom;
  box-shadow: inset 0.25em 0.25em 0.25em rgba(255, 255, 255, 0.25), inset -0.25em -0.25em 0.25em 0.5em rgba(0, 0, 0, 0.25), inset 1em 0.5em 0.5em rgba(0, 0, 0, 0.5);
}
.led:before {
  content: '';
  border-radius: 50%;
  display: block;
  width: 0.25em;
  height: 0.25em;
  background: #fff;
  opacity: 0.1;
  margin-top: 0.2em;
  margin-left: 0.2em;
  mix-blend-mode: overlay;
}
.led.led-xs {
  font-size: 50%;
}
.led.led-sm {
  font-size: 80%;
}
.led.on {
  box-shadow: 0 0 0.25em 0.1em, 0 0 1em 0.5em;
  border: 2px solid rgba(0, 0, 0, 0.05);
}
.led.on.blink {
  -webkit-animation: blink 0.5s infinite;
  -moz-animation: blink 0.5s infinite;
  -o-animation: blink 0.5s infinite;
  animation: blink 0.5s infinite;
}
@keyframes blink {
  0% {
    border: 1px solid rgba(0, 0, 0, 0.75);
    box-shadow: inset 0.25em 0.25em 0.25em rgba(255, 255, 255, 0.25), inset -0.25em -0.25em 0.25em 0.5em rgba(0, 0, 0, 0.25), inset 1em 0.5em 0.5em rgba(0, 0, 0, 0.5);
  }
  50% {
    border: 2px solid rgba(0, 0, 0, 0.05);
    box-shadow: 0 0 0.25em 0.1em, 0 0 1em 0.5em;
  }
  100% {
    border: 1px solid rgba(0, 0, 0, 0.75);
    box-shadow: inset 0.25em 0.25em 0.25em rgba(255, 255, 255, 0.25), inset -0.25em -0.25em 0.25em 0.5em rgba(0, 0, 0, 0.25), inset 1em 0.5em 0.5em rgba(0, 0, 0, 0.5);
  }
}