.perspective-1000 { 
    perspective: 1000px; 
}
.transform-style-3d { 
    transform-style: preserve-3d; 
}
.backface-hidden { 
    backface-visibility: hidden; 
}
.rotate-y-180 { 
    transform: rotateY(180deg); 
}
@keyframes fadeIn {
    from { opacity: 0; transform: scale(0.95); }
    to { opacity: 1; transform: scale(1); }
}
.animate-fadeIn {
    animation: fadeIn 0.25s ease-out forwards;
}
/* Efecto de volteo suave y fluido */
.transition-transform {
    transition: transform 0.6s cubic-bezier(0.4, 0, 0.2, 1);
}
/* Borde rojo de error ultra visible con resplandor neón */
.error-card {
    border: 3px solid #ef4444 !important;
    box-shadow: 0 0 30px 5px rgba(239, 68, 68, 0.85) !important;
}
/* Borde verde de acierto ultra visible con resplandor neón */
.match-card {
    border: 3px solid #10b981 !important;
    box-shadow: 0 0 30px 5px rgba(16, 185, 129, 0.85) !important;
}