.product-item img {
    width: 100%;
    height: 250px;
    object-fit: contain;
}

.product-item {
    display: flex;
    flex-direction: column;
}

.product-item .btn {
    margin-top: auto;
}

.product-item .btn {
    margin-top: auto;
    align-self: center;
    padding: 8px 20px; /* biraz daha dengeli */
}