* {
box-sizing: border-box;
}

body {
font-size: 20px;
max-width: 1280px;
margin: auto;
padding: 1em;
}

img {
max-width: 100%;
}

.main-nav {
list-style-type: none;
}

hr{
margin-top: 50px;
}
ul {
    justify-content: flex-end;
    list-style: none;
    display: flex;
}
li {
    margin: 0.5em;
}

main {
    display: flex;
    flex-wrap: wrap;
}

@media screen and (min-width: 900px) {
    .media-card {
        display: flex;
    }
    .gallery {
        display: flex;
        flex-wrap: wrap;
    }
    .gallery .media-card {
        margin: 0.5em;
        max-width: 48%;
    }
    h1 {
        margin-top: 0;
    }
    img {
        padding: 1em;
    }
}