#logout-countdown {
  position: relative;
  overflow: hidden;
}

#logout-countdown::before {
  content: '';
  position: absolute;
  inset: 0;
  border-radius: inherit;           /* matches button's own radius */
  padding: 1px;                     /* border thickness */
  background: conic-gradient(
    transparent var(--progress, 0%),
    rgb(var(--bs-danger-rgb)) 0%
  );
  -webkit-mask:
    linear-gradient(#fff 0 0) content-box,
    linear-gradient(#fff 0 0);
  -webkit-mask-composite: xor;
  mask-composite: exclude;
}