.grid-sizer,
.grid-item {
    width: 99%;
    margin-bottom: 40px;
    border-radius: 15px;
    background-color: lightgray;
}

.gutter-sizer {
    width: 1%;
}

.grid-container {
    margin: 0 auto;
}

.grid-item:hover {
    filter: opacity(0.9);
}

@media only screen and (min-width: 576px) {

    .grid-sizer,
    .grid-item {
        width: 49%;
        background-color: lightgray;
    }
}

@media only screen and (min-width: 992px) {

    .grid-sizer,
    .grid-item {
        width: 32%;
        background-color: lightgray;
    }
}

@media only screen and (min-width: 1200px) {

    .grid-sizer,
    .grid-item {
        width: 24%;
        background-color: lightgray;
    }
}