remote.css

body {
    background:pink;
}
body::after {
    display: block;
    position: absolute;
    top: 0;
    right: 0;
    padding: 0.5em;
    background: red;
    color: #fff;
    font-size: 0.7em;
    font-family: Courier;
    content: "Remote CSS";
    opacity: 0.5;
}