.mensaje-emergente {
    position: fixed;
    bottom: 30px;
    right: 30px;
    background-color: #B93636;
    color: white;
    padding: 15px 25px;
    border-radius: 8px;
    box-shadow: 0 0 10px rgba(0,0,0,0.3);
    z-index: 1000;
    opacity: 0;
    animation: fadeInOut 4s forwards;
}
@keyframes fadeInOut {
    0%   { opacity: 0; transform: translateY(20px); }
    10%  { opacity: 1; transform: translateY(0); }
    90%  { opacity: 1; }
    100% { opacity: 0; transform: translateY(0px); }
}