:root { --pulse-size: 14px; }
.pulse { font-weight: 600; color:#666; }
.pulse.on::before, .pulse.off::before{
  content:""; display:inline-block; width:var(--pulse-size); height:var(--pulse-size);
  border-radius:50%; margin-right:10px; vertical-align:-2px;
}
.pulse.off::before { background:#adb5bd; }
.pulse.on { color:#e03131; }
.pulse.on::before {
  background:#fa5252; box-shadow:0 0 0 0 rgba(250,82,82,.7);
  animation:pulse 1.25s infinite;
}
@keyframes pulse {
  0%{box-shadow:0 0 0 0 rgba(250,82,82,.7);} 70%{box-shadow:0 0 0 12px rgba(250,82,82,0);} 100%{box-shadow:0 0 0 0 rgba(250,82,82,0);}
}