.rigel-back-to-top {
  --btt-size: 58px;
  --btt-gold: #c9a86a;
  --btt-gold-soft: #e4c88a;
  --btt-green: #1f2d24;
  --btt-green-mid: #2a3b30;
  position: fixed;
  right: clamp(16px, 3vw, 28px);
  bottom: clamp(16px, 3vw, 28px);
  z-index: 99990;
  width: var(--btt-size);
  height: var(--btt-size);
  padding: 0;
  border: none;
  border-radius: 50%;
  cursor: pointer;
  background: linear-gradient(145deg, var(--btt-green-mid) 0%, var(--btt-green) 100%);
  color: var(--btt-gold-soft);
  box-shadow:
    0 10px 28px rgba(15, 22, 17, 0.35),
    0 0 0 1px rgba(201, 168, 106, 0.35);
  opacity: 0;
  visibility: hidden;
  transform: translateY(18px) scale(0.88);
  transition:
    opacity 0.35s cubic-bezier(0.22, 1, 0.36, 1),
    transform 0.35s cubic-bezier(0.22, 1, 0.36, 1),
    visibility 0.35s,
    box-shadow 0.25s ease,
    background 0.25s ease;
  -webkit-tap-highlight-color: transparent;
}

.rigel-back-to-top.is-visible {
  opacity: 1;
  visibility: visible;
  transform: translateY(0) scale(1);
}

.rigel-back-to-top:hover {
  background: linear-gradient(145deg, #354a3d 0%, var(--btt-green-mid) 100%);
  box-shadow:
    0 14px 36px rgba(15, 22, 17, 0.42),
    0 0 0 2px rgba(201, 168, 106, 0.55);
  color: #fff;
}

.rigel-back-to-top:focus-visible {
  outline: 3px solid var(--btt-gold);
  outline-offset: 4px;
}

.rigel-back-to-top__ring {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  transform: rotate(-90deg);
  pointer-events: none;
}

.rigel-back-to-top__track,
.rigel-back-to-top__progress {
  fill: none;
  stroke-width: 2.5;
}

.rigel-back-to-top__track {
  stroke: rgba(247, 245, 241, 0.12);
}

.rigel-back-to-top__progress {
  stroke: var(--btt-gold);
  stroke-linecap: round;
  transition: stroke-dashoffset 0.12s linear;
}

.rigel-back-to-top__arrow {
  position: relative;
  z-index: 1;
  display: flex;
  align-items: center;
  justify-content: center;
  width: 100%;
  height: 100%;
}

.rigel-back-to-top__arrow svg {
  width: 22px;
  height: 22px;
  display: block;
  transition: transform 0.25s ease;
}

.rigel-back-to-top:hover .rigel-back-to-top__arrow svg {
  transform: translateY(-3px);
}

.rigel-back-to-top.is-visible .rigel-back-to-top__arrow svg {
  animation: rigel-btt-bob 2.4s ease-in-out infinite;
}

@keyframes rigel-btt-bob {
  0%,
  100% {
    transform: translateY(0);
  }
  50% {
    transform: translateY(-4px);
  }
}

@media (max-width: 560px) {
  .rigel-back-to-top {
    --btt-size: 54px;
    right: 14px;
    bottom: 14px;
  }

  .rigel-back-to-top__arrow svg {
    width: 20px;
    height: 20px;
  }
}

@media (prefers-reduced-motion: reduce) {
  .rigel-back-to-top,
  .rigel-back-to-top.is-visible .rigel-back-to-top__arrow svg {
    transition: opacity 0.2s ease, visibility 0.2s;
    animation: none;
  }

  .rigel-back-to-top__progress {
    transition: none;
  }
}