#tstt-btn {
    opacity: 0;
    visibility: hidden;
    position: fixed;
    z-index: 999999;
    border: none;
    outline: none;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    box-shadow: 0 4px 10px rgba(0,0,0,0.15);
    transition: opacity 0.3s ease, visibility 0.3s ease, transform 0.3s ease, background-color 0.3s ease, color 0.3s ease;
}

#tstt-btn.tstt-visible {
    opacity: 1;
    visibility: visible;
}

#tstt-btn:hover {
    transform: translateY(-5px);
    box-shadow: 0 6px 15px rgba(0,0,0,0.2);
}

#tstt-btn svg {
    display: block;
}

@media (max-width: 768px) {
    #tstt-btn.tstt-hide-mobile {
        display: none !important;
    }
}