/* The Back to Top button, wherever a page carries one.
 *
 * It used to be defined in css/index/utilities.css alone, so branch/videos.html
 * and branch/find-tutors.html - which both ship the button in their markup but
 * do not load that sheet - drew it as a plain, unstyled, always-visible button
 * sitting in the document flow under the footer. That stray arrow is what this
 * file fixes: `position: fixed` takes it out of the flow, and `visibility:
 * hidden` keeps it out of sight until js/shared/back-to-top.js says otherwise.
 *
 * One definition, loaded by every page with the button (index included) - two
 * copies of these rules is how the arrow came to look right on one page and
 * broken on the next.
 */
.back-to-top {
    position: fixed;
    bottom: 2rem;
    right: 2rem;
    width: 50px;
    height: 50px;
    background: linear-gradient(135deg, var(--button-bg), var(--button-hover));
    color: white;
    border: none;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    opacity: 0;
    visibility: hidden;
    transition: all 0.3s ease;
    z-index: 1000;
    box-shadow: 0 5px 20px rgba(var(--button-bg-rgb), 0.3);
}

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

.back-to-top:hover {
    transform: translateY(-5px);
    box-shadow: 0 10px 30px rgba(var(--button-bg-rgb), 0.4);
}