<div class="cards">
    <div class="card_item"></div>
</div>

.cards {
    margin: 0;
    padding: 0;
    position: relative; /*!*/
}

.card_item {
    position: absolute; /*!*/
    left: 50%;          /*!*/
    margin-right: -50%; /*!*/
    transform: translate(-50%, 0); /*!*/
    height: 500px;
    width: 300px;
    background-color: rgb(59, 59, 59);
}