.progress {
  --progress-color: #fff;
  --progress-line: rgba(255, 255, 255, .28);
  --progress-x: 0%;
  height: 10px;
  background: none;
  display: flex;
  align-items: flex-end;
  justify-content: space-between;
  pointer-events: none;
}

.progress::before {
  content: '';
  position: absolute;
  left: 0;
  right: 0;
  bottom: 0;
  height: 1px;
  background: var(--progress-line);
}

.progress i {
  position: absolute;
  z-index: 2;
  left: var(--progress-x);
  bottom: 0;
  width: 1px;
  height: 9px;
  background: var(--progress-color);
  opacity: .72;
  transform: translateX(-50%);
  transform-origin: center bottom;
  will-change: left;
}

.progress span {
  position: relative;
  z-index: 1;
  flex: 0 0 1px;
  width: 1px;
  height: var(--tick-height, 1px);
  border: 0;
  border-radius: 0;
  background: var(--progress-color);
  opacity: var(--tick-opacity, .18);
  transform: none;
  transform-origin: center bottom;
  will-change: height, opacity;
}

.progress span.is-major {
  min-height: 2px;
}

.progress b {
  position: absolute;
  z-index: 3;
  left: var(--detent-x);
  bottom: -2px;
  width: 5px;
  height: 5px;
  border: 1px solid var(--progress-color);
  background: transparent;
  opacity: .34;
  transform: translateX(-50%) rotate(45deg) scale(.72);
  transform-origin: center;
  transition: opacity .24s ease, background .24s ease, transform .32s cubic-bezier(.2,.75,.2,1);
}

.progress b.is-complete {
  background: var(--progress-color);
  opacity: .68;
}

.progress b.is-current {
  background: var(--progress-color);
  opacity: 1;
  transform: translateX(-50%) rotate(45deg) scale(1);
}

@media (max-width: 720px) {
  .progress { height: 9px; }
  .progress i { height: 8px; }
  .progress b { width: 4px; height: 4px; }
}

@media (prefers-reduced-motion: reduce) {
  .progress i,
  .progress span { will-change: auto; }
  .progress b { transition: none; }
}