*,
*::before,
*::after {
    box-sizing: border-box;
}

body {
    font-family: sans-serif;
    background-color: #186d2d;
}

h1 {
    text-align: center;
    margin: 40px auto;
    letter-spacing: 0.25em;
    color: whitesmoke;
}

.img-container {
    max-width: 680px;
    margin: 20px auto;
}

.img-container::after {
    content: " ";
    display: block;
    clear: both;
}

img {
    display: block;
    float: left;
    width: 48%;
    height: 270px;
    margin: 1%;
    cursor: pointer;
    object-fit: cover;
    border-radius: 8px;
    box-shadow: 0 4px 8px 0 rgba(0,0,0,1);
    transition: 0.3s;
}