.back-to-top {
  position: fixed;
  bottom: 90px;
  right: 5px;
  display: none;
  background-color: #444;
  color: white;
  font-size: 1.5em; /* menší než předchozí */
  width: 40px;
  height: 40px;
  border-radius: 50%;
  text-align: center;
  line-height: 40px;
  cursor: pointer;
  box-shadow: 0 4px 8px rgba(0, 0, 0, 0.5);
  transition: background-color 0.3s ease, transform 0.4s ease, opacity 0.3s ease;
  z-index: 1000;
  opacity: 0;
  transform: translateY(20px);
}

/* Show the button when scrolling down */
.back-to-top.show {
  display: block;
  opacity: 1;
  transform: translateY(0);
}

/* Hover efekt */
.back-to-top:hover {
  background-color: #666;
}

/* Kliknutí = změna barvy na crimson */
.back-to-top.clicked {
  background-color: crimson;
}