Как исправить продукт с сеткой строк с фиксированным размером?

.product-grid4, .product-grid4 .product-image4 {
    position: relative
}

.product-grid4 {
    font-family: Poppins,sans-serif;
    text-align: center;
    border-radius: 5px;
    overflow: hidden;
    z-index: 1;
    transition: all .3s ease 0s
}

    .product-grid4:hover {
        box-shadow: 0 0 10px rgba(0,0,0,.2)
    }

    .product-grid4 .product-image4 a {
        display: block
    }

    .product-grid4 .product-image4 img {
        width: 100%;
        height: auto
    }

    .product-grid4 .pic-1 {
        opacity: 1;
        transition: all .5s ease-out 0s
    }

    .product-grid4 .product-discount-label, .product-grid4 .product-new-label {
        color: #fff;
        background-color: #16a085;
        font-size: 13px;
        font-weight: 800;
        text-transform: uppercase;
        line-height: 45px;
        height: 45px;
        width: 45px;
        border-radius: 50%;
        position: absolute;
        left: 10px;
        top: 15px;
        transition: all .3s
    }

    .product-grid4 .product-discount-label {
        left: auto;
        right: 10px;
        background-color: #d7292a
    }

    .product-grid4 .product-content {
        padding: 25px
    }

    .product-grid4 .title {
        font-size: 15px;
        font-weight: 400;
        text-transform: capitalize;
        margin: 0 0 7px;
        transition: all .3s ease 0s
    }

        .product-grid4 .title a {
            color: #222
        }

    .product-grid4 .price {
        color: #16a085;
        font-size: 17px;
        font-weight: 700;
        margin: 0 2px 15px 0;
        display: block
    }

        .product-grid4 .price span {
            color: #909090;
            font-size: 13px;
            font-weight: 400;
            letter-spacing: 0;
            text-decoration: line-through;
            text-align: left;
            vertical-align: middle;
            display: inline-block
        }

    .product-grid4 .add-to-cart {
        border: 1px solid #16a085;
        display: inline-block;
        padding: 10px 20px;
        color: #fff;
        background: #16a085;
        font-weight: 600;
        font-size: 14px;
        border-radius: 4px;
        transition: all .3s
    }


 
@media only screen and (max-width:990px) {
    .product-grid4 {
        margin-bottom: 30px
    }
}

<div class = "container">
        <div class = "row">
            <div class = "col-md-3 col-sm-6 col-xs-6">
                <div class = "product-grid4">
                    <div class = "product-image4">
                        <a href = "#">
                            <img class = "pic-1" src = "img/pic1.jpg">
                        </a>
                        <span class = "product-new-label">New</span>
                        <span class = "product-discount-label">50%</span>
                    </div>
                    <div class = "product-content">
                        <h3 class = "title">Burger Bosku</h3>
                        <div class = "price">
                           RM 10.00
                            <span>RM 20.00</span>
                        </div>
                        <button class = "add-to-cart" data-toggle = "modal" data-target = "#modalCart">+ Add To Cart</button>
                    </div>
                </div>
            </div>
            <div class = "col-md-3 col-sm-6 col-xs-6">
                <div class = "product-grid4">
                    <div class = "product-image4">
                        <a href = "#">
                            <img class = "pic-1" src = "img/pic2.jpg">
                        </a>
                        <span class = "product-discount-label">50%</span>
                    </div>
                    <div class = "product-content">
                        <h3 class = "title">Pasta Special</h3>
                        <div class = "price">
                            RM 15.00
                            <span>RM 30.00</span>
                        </div>
                        <button class = "add-to-cart" data-toggle = "modal" data-target = "#modalCart">+ Add To Cart</button>
                    </div>
                </div>
            </div>
            <div class = "col-md-3 col-sm-6 col-xs-6">
                <div class = "product-grid4">
                    <div class = "product-image4">
                        <a href = "#">
                            <img class = "pic-1" src = "img/pic4.jpg">
                        </a>
                        <span class = "product-new-label">New</span>
                        <span class = "product-discount-label">10%</span>
                    </div>
                    <div class = "product-content">
                        <h3 class = "title"><a href = "#">Pizza Pizzi</a></h3>
                        <div class = "price">
                            RM 9.00
                            <span>RM 10.00</span>
                        </div>
                        <button class = "add-to-cart" data-toggle = "modal" data-target = "#modalCart">+ Add To Cart</button>
                    </div>
                </div>
            </div>
            <div class = "col-md-3 col-sm-6 col-xs-6">
                <div class = "product-grid4">
                    <div class = "product-image4">
                        <a href = "#">
                            <img class = "pic-1" src = "img/pic7.jpg">
                        </a>
                        <span class = "product-new-label">New</span>
                        <span class = "product-discount-label">20%</span>
                    </div>
                    <div class = "product-content">
                        <h3 class = "title">Sweet Food</h3>
                        <div class = "price">
                            RM 18.00
                            <span>RM 20.00</span>
                        </div>
                        <button class = "add-to-cart" data-toggle = "modal" data-target = "#modalCart">+ Add To Cart</button>
                    </div>
                </div>
            </div>
        </div>
    </div>
    <hr>