#scrollTopBtn {
  position: fixed;
  bottom: 30px;
  right: 30px;
  width: 50px;
  height: 50px;
  border-radius: 50%;
  background: transparent;
  border: none;
  cursor: pointer;
  opacity: 0;
  visibility: hidden;
  transform: scale(0.5);
  transition: opacity 0.3s ease, visibility 0.3s ease, transform 0.3s cubic-bezier(0.175, 0.885, 0.32, 1.275);
  z-index: 9999;
  display: flex;
  align-items: center;
  justify-content: center;
  filter: drop-shadow(0 2px 4px rgba(194, 58, 64, 0.2));
}

#scrollTopBtn.show {
  opacity: 1;
  visibility: visible;
  transform: scale(1);
}

#scrollTopBtn .arrow {
  font-size: 22px;
  font-weight: 800;
  z-index: 2;
  margin-top: -2px;
}

.progress-circle {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  transform: rotate(-90deg);
}

.progress-circle circle.track {
  fill: none;
  stroke-width: 2;
}

.progress-circle circle.progress {
  fill: none;
  stroke-width: 2;
  stroke-linecap: round;
  transition: stroke-dashoffset 0.1s linear;
}