@keyframes fadeInSerene {
    from { opacity: 0; transform: translateY(4px); }
    to { opacity: 1; transform: translateY(0); }
}

#resultat-box:not(.hidden) {
    animation: fadeInSerene 0.4s cubic-bezier(0.16, 1, 0.3, 1) forwards;
}

input, button {
    transition: all 0.2s ease;
}