.back-to-top {
    position: fixed;
    bottom: 4.5rem;
    right: 0;
    width: 45px;
    height: 45px;
    color: white;
    border: none;
    cursor: pointer;
    font-size: 20px;
    opacity: 0;
    visibility: hidden;
    transition: all 0.3s ease;
    display: flex;
    align-items: center;
    justify-content: center;
    filter: drop-shadow(0 0 6px #ffed47);
    left: 80%;
}
.back-to-top:hover { 
  transform: translateY(-2px);
}

.back-to-top.visible {
  opacity: 1;
  visibility: visible;
}