/* --------------------------------------------------
   Back to Top Button - AI Platform Style
   -------------------------------------------------- */
.back-to-top {
    position: fixed;
    bottom: var(--ai-space-6);
    right: var(--ai-space-6);
    width: 48px;
    height: 48px;
    background: var(--ai-gradient-primary);
    color: #ffffff;
    border: none;
    border-radius: 50%;
    cursor: pointer;
    opacity: 0;
    visibility: hidden;
    transform: translateY(20px);
    transition: all var(--ai-transition);
    box-shadow: 0 4px 14px rgba(99, 102, 241, 0.4);
    z-index: 9999;
    display: flex;
    align-items: center;
    justify-content: center;
}

.back-to-top.visible {
    opacity: 1;
    visibility: visible;
    transform: translateY(0);
}

.back-to-top:hover {
    transform: translateY(-4px);
    box-shadow: 0 6px 20px rgba(99, 102, 241, 0.5);
}

.back-to-top:focus {
    outline: 2px solid var(--ai-primary-400);
    outline-offset: 3px;
}

.back-to-top svg {
    width: 20px;
    height: 20px;
}

@media (max-width: 768px) {
    .back-to-top {
        bottom: var(--ai-space-4);
        right: var(--ai-space-4);
        width: 44px;
        height: 44px;
    }
}