.add-btn {
    width: 90%;
    display: block;
    margin: 20px auto;
    font-size: 1rem;
    font-weight: bold;
    border: none;
    background-color: #e4393c;
    color: white;
    padding: 0.8rem 3rem;
    border-radius: 2rem;
    text-align: center;
    animation: btnScale 0.5s linear infinite alternate;
}

@keyframes btnScale {
    0% {
        transform: scale(1);
    }
    100% {
        transform: scale(0.95);
    }
}