function create_prologue() {
    let back_to_index = document.createElement("a");
    back_to_index.setAttribute("href", "../index.html");
    back_to_index.innerHTML = "Back to index";

    let title = document.createElement("h1");
    title.innerText = document.title;

    let body = document.getElementsByTagName("body")[0];
    body.insertBefore(title, body.firstChild);
    body.insertBefore(back_to_index, body.firstChild);
}