Add the red part to this statement:

.cartProductDisplay, .cartUnitDisplay, .cartTotalDisplay, .cartRemoveItemDisplay, .cartQuantityUpdate, .cartQuantity, #cartInstructionsDisplay, .cartTotalsDisplay {
padding: 0.5em 0em;
border-bottom:1px solid;
}


then add this to the stylesheet:


.cartProductImage {border-bottom:1px solid;}

You may have to play with margins and padding.