bh_highlight.user.js

// ==UserScript==
// @name         bh + highlight.js
// @namespace    https://www.blast.hk/
// @author       imring
// @match        https://www.blast.hk/attachments/*/plain
// @icon         https://www.google.com/s2/favicons?domain=blast.hk

// @require      https://code.jquery.com/jquery-3.6.0.min.js
// @require      https://cdnjs.cloudflare.com/ajax/libs/highlight.js/10.7.1/highlight.min.js
// @require      https://cdnjs.cloudflare.com/ajax/libs/highlight.js/10.7.1/languages/go.min.js

// @resource     IMPORTED_CSS https://cdnjs.cloudflare.com/ajax/libs/highlight.js/10.7.1/styles/stackoverflow-dark.min.css
// @grant        GM_getResourceText
// @grant        GM_addStyle
// ==/UserScript==

$(document).ready(function() {
    const my_css = GM_getResourceText("IMPORTED_CSS");
    GM_addStyle(my_css);

    let pre = $("body").find("pre");
    let text = pre.text();
    pre.remove();

    $("body").append(`<pre><code>${text}</code></pre>`);

    hljs.highlightBlock($("body").find("pre code").get(0));

    let bgcolor = $(".hljs").css("background");
    $("body, pre").css({
        "margin": "0",
        "padding": "0",
        "background": bgcolor,
        "word-wrap": "break-word",
        "white-space": "pre-wrap"
    });
});

(function() {
    'use strict';
})();