.scroll-to-top-btn {
  position: fixed;
  bottom: 32px;
  right: 32px;
  z-index: 999;
  width: 64px;
  height: 64px;
  background: #2563eb;
  border-radius: 50%;
  box-shadow: 0 4px 24px rgba(38, 99, 235, 0.15);
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  transition: box-shadow 0.2s, background 0.2s;
  border: none;
  outline: none;
}
.scroll-to-top-btn:hover {
  background: #1742a0;
  box-shadow: 0 8px 32px rgba(38, 99, 235, 0.25);
}
.scroll-to-top-btn i {
  color: #fff;
  font-size: 2rem;
}
@media (max-width: 600px) {
  .scroll-to-top-btn {
    width: 48px;
    height: 48px;
    bottom: 16px;
    right: 16px;
  }
  .scroll-to-top-btn i {
    font-size: 1.5rem;
  }
}