.bottom-to-top-btn {
    position: fixed;
    width: 45px;
    height: 45px;
    bottom: 40px;
    right: 30px;
    background-color: var(--primary);
    color: #cbcaca;
    border-radius: 5px;
    text-align: center;
    z-index: 1001;
    visibility: hidden;
    opacity: 0;
    border: 1px solid #c3c3c3;
    transition: opacity 0.25s ease, visibility 0.25s ease;
}
.bottom-to-top-btn.active {
    opacity: 1;
    visibility: visible;
}