.rth-wrapper {
    position: fixed;
    z-index: 9999;
    opacity: 0;
    visibility: hidden;
    transition: opacity 0.3s ease, visibility 0.3s ease, transform 0.3s ease;
    transform: translateY(20px);
}

body.admin-bar .rth-wrapper {
    /* Offset for admin bar if needed, though usually back to top is at bottom */
}

.rth-wrapper.is-visible {
    opacity: 1;
    visibility: visible;
    transform: translateY(0);
}

/* Positioning rules */
.rth-wrapper.pos-right {
    right: 25px;
    bottom: 25px;
}

.rth-wrapper.pos-left {
    left: 25px;
    bottom: 25px;
}

.rth-wrapper.pos-center {
    left: 50%;
    transform: translateX(-50%) translateY(20px);
    bottom: 25px;
}

.rth-wrapper.pos-center.is-visible {
    transform: translateX(-50%) translateY(0);
}

/* Button design */
.rth-btn {
    display: flex;
    align-items: center;
    justify-content: center;
    border: none;
    cursor: pointer;
    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.15);
    transition: background-color 0.3s ease, color 0.3s ease, transform 0.2s ease, box-shadow 0.3s ease;
    padding: 0;
}

.rth-btn:hover {
    transform: scale(1.08);
    box-shadow: 0 6px 20px rgba(0, 0, 0, 0.2);
}

.rth-btn:active {
    transform: scale(0.95);
}

.rth-btn svg {
    transition: fill 0.3s ease;
}