#back-to-top-container {
    position: fixed;
    bottom: 30px;
    right: 30px;
    visibility: hidden;
    opacity: 0;
    width: 50px;
    height: 50px;
    z-index: 1000;
    transition: opacity 0.3s ease, visibility 0.3s ease;
    transform: scale(0.8);
    transition: all 0.3s ease;
}

#back-to-top-container.visible {
    transform: scale(1);
    visibility: visible;
    opacity: 1;
}

#back-to-top {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    border-radius: 50%;
    background-color: #333;
    color: white;
    font-size: 20px;
    cursor: pointer;
    opacity: 0.7;
    transition: opacity 0.3s, transform 0.3s;
    z-index: 2;
    border: 1px solid #980505;
    box-shadow: 0 0 15px #666;
}

#back-to-top:hover {
    opacity: 0.9;
    transition: opacity 0.3s, transform 0.3s;
}

#progress-ring {
    position: absolute;
    top: 0;
    left: 0;
    z-index: 1;
}

.ring-bg {
    stroke: #555;
    stroke-opacity: 0.3;
}

.ring-progress {
    transition: stroke-dashoffset 0.3s ease-out;
}