.back-to-top-button {
    display: none;
    position: fixed;
    bottom: 20px;
    right: 20px;
    width: 40px;
    height: 40px;
    line-height: 40px;
    text-align: center;
    font-size: 20px;
    color: #fff;
    background: #333;
    border-radius: 50%;
    box-shadow: 0 2px 6px rgba(0, 0, 0, 0.3);
    z-index: 999;
    transition: opacity 0.3s ease-in-out;
}

.back-to-top-button:hover {
    opacity: 0.8;
}

.back-to-top-button.show {
    display: block;
}
.back-to-top-button .svg-icon {
    top: 4px;
    left: 2px;
}

.svg-icon {
    margin-right: 3px;
    position: relative;
    top: 3px;
}