.dual-ring {
  display: inline-block;
  width: 56px;
  height: 56px;
}
.dual-ring:after {
  content: " ";
  display: block;
  width: 32px; /* dual-ring width - 2xMargin - 2xBorder */
  height: 32px;
  margin: 8px;
  border-radius: 50%;
  border: 4px solid #8c8c8c;
  border-color: #8c8c8c transparent #8c8c8c transparent;
  animation: dual-ring 1.2s linear infinite;
}
.dual-ring-small {
  display: inline-block;
  width: 26px;
  height: 26px;
}
.dual-ring-small:after {
  content: " ";
  display: block;
  width: 13px; /* dual-ring width - 2xMargin - 2xBorder */
  height: 13px;
  margin: 5px;
  border-radius: 50%;
  border: 2px solid #8c8c8c;
  border-color: #8c8c8c transparent #8c8c8c transparent;
  animation: dual-ring 1.2s linear infinite;
}
.dual-ring-flex {
  display: flex;
  align-content: center;
}
.dual-ring-flex:after {
  content: " ";
  display: block;
  width: 8px; /* dual-ring width - 0xMargin - 2xBorder */
  height: 8px;
  margin: 0px;
  border-radius: 50%;
  border: 2px solid #8c8c8c;
  border-color: #8c8c8c transparent #8c8c8c transparent;
  animation: dual-ring 1.2s linear infinite;
}
.dual-ring-flex.bg:after {
  border: 2px solid var(--pri-background);
  border-color: var(--pri-background) transparent var(--pri-background) transparent;
}
.dual-ring-flex.fg:after {
  border: 2px solid var(--sec-label);
  border-color: var(--sec-label) transparent var(--sec-label) transparent;
}
@keyframes dual-ring {
  0%   { transform: rotate(0deg);   }
  100% { transform: rotate(360deg); }
}