/**
 * Back to Top Button
 * Floating button that appears when the user scrolls down
 */

.back-to-top-btn {
    position: fixed;
    bottom: var(--spacing-5);
    right: var(--spacing-5);
    z-index: 1000;
    width: 44px;
    height: 44px;
    padding: 0;
    line-height: 1;
    border-radius: 50%;
    border: 1px solid var(--color-border);
    background: var(--color-bg);
    color: var(--color-text);
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    opacity: 0;
    transform: translateY(12px);
    transition: opacity 0.25s ease, transform 0.25s ease, background-color 0.15s ease;
    pointer-events: none;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.12);
}

.back-to-top-btn.visible {
    opacity: 1;
    transform: translateY(0);
    pointer-events: auto;
}

.back-to-top-btn:hover {
    background: var(--color-primary);
    color: var(--color-bg);
    border-color: var(--color-primary);
}

.back-to-top-btn svg {
    width: 20px;
    height: 20px;
    flex-shrink: 0;
    stroke: currentColor;
}