/* Advanced Back to Top Button with Water Effect */
.back-to-top {
    position: fixed;
    bottom: 30px;
    right: 30px;
    width: 60px;
    height: 60px;
    background: var(--gradient);
    color: white;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.5rem;
    box-shadow: 0 10px 25px rgba(108, 99, 255, 0.4);
    cursor: pointer;
    opacity: 0;
    visibility: hidden;
    transition: var(--transition);
    z-index: 99;
    overflow: hidden;
}

.back-to-top::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(255, 255, 255, 0.1);
    border-radius: 50%;
    transform: scale(0);
    transition: transform 0.5s ease;
}

.back-to-top:hover::before {
    transform: scale(1);
}

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

.back-to-top:hover {
    transform: translateY(-5px) scale(1.1);
    box-shadow: 0 15px 30px rgba(108, 99, 255, 0.6);
}

.water-fill {
    position: absolute;
    bottom: 0;
    left: 0;
    width: 100%;
    background: rgba(255, 255, 255, 0.3);
    border-radius: 50% 50% 0 0;
    transition: height 0.3s ease;
}