style.css

* {
    margin: 0;
    padding: 0;
    user-select: none;
    box-sizing: border-box;
}

body {
    background: #fff;
    text-align: center;
}

h2 {
    text-align: center;
    margin-top: 30px;
    font-size: 40px;
    font-family: sans-serif;
}

.slider {
    display: flex;
    height: 80%;
    width: 100%;
    margin: 5% auto 0;
    box-sizing: border-box !important;
}

.imagebox {
    margin: 0 1%;
    flex-grow: 1;
    flex-basis: 0;
    transition: 1s;
}

.imagebox img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    transition: 1s;
    object-fit: cover;
}

.imagebox:hover {
    width: 320px;
    height: 525px;
    transition: 1s;
}

.imagebox:hover, .active {
    flex-basis: 50%;
}

.slider:hover .active {
    flex-basis: 0;
}

@media screen and (min-width: 300px) and (max-width: 800px) {
    .slider {
        flex-direction: column;
        justify-content: center;
        align-items: center;
        overflow: hidden;
    }

    .imagebox {
        width: 250px;
        height: 200px;
        margin: 30px 0px;
    }

    .imagebox:hover {
        width: 320px;
        height: 250px;
    }

    .imagebox:hover img {
        width: 320px;
        height: 250px;
        flex-basis: 100%;
    }

    .imagebox img {
        width: 250px;
        height: 200px;
    }
}