html {
    box-sizing: border-box;
}

*, a:before, a:after {
    box-sizing: inherit;
}

body {
    background: black;
}


main {
    margin: 0 auto;
    width: 50%;
}

.poster {
    margin: 1em;
    position: relative;
    left: 0;
    top: 0;
}

.poster .body {
    max-width: 100%;
    position: relative;
    top: 0;
    left: 0;
}

.poster .rsvp {
    position: absolute;
    top: calc(0.22 * 100%);
    right: 30px;
    width: calc(.18 * 100%);
}

@media (max-width: 1024px) {
    main {
        width: 100%;
    }

    .poster .rsvp {
        top: calc(0.2 * 100);
    }
}