.bg-switcher {
  position: fixed;
  right: 24px;
  bottom: 24px;
  z-index: 200;
  width: 48px;
  height: 48px;
  border-radius: 50%;
  background: rgba(255,255,255,0.92) ;
  border: none;
  box-shadow: 0 2px 12px #0002;
  font-size: 1.6em;
  color: #4f8cff;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: background 0.18s, box-shadow 0.18s;
  opacity: 0.7;
}
.bg-switcher:hover {
  background: #eaf6ff;
  box-shadow: 0 4px 24px #4f8cff22;
}