Custom GitHub profile CSS by creating `.custard/style.css` in your special repository.

custard.user.js

// ==UserScript==
// @name         custard
// @namespace    exurd.custard
// @version      4
// @description  custom github profile css
// @author       exurd
// @match        https://github.com/*
// @connect      raw.githubusercontent.com
// @icon         https://www.google.com/s2/favicons?sz=64&domain=github.com
// @grant        GM_addStyle
// @grant        GM_xmlhttpRequest
// ==/UserScript==

const CSS_MARKER = '/* custard-profile-style */';

(function() {
    'use strict';

    let currentProfile = null;

    function cleanupStyles() {
        document.querySelectorAll('style').forEach(e => {
            if (e.textContent.includes(CSS_MARKER)) {
                e.remove();
            }
        });
    }

    function applyCustomStyle() {
        const path = window.location.pathname.replace(/^\/|\/$/g, '');
        const parts = path.split('/');
        const username = (parts.length === 1 && parts[0]) ? parts[0] : null;

        if (username === currentProfile) {
            return;
        }
        currentProfile = username;

        cleanupStyles();

        if (!username) {
            return;
        }

        const cssUrl = `https://raw.githubusercontent.com/${username}/${username}/main/.custard/style.css`;
        GM_xmlhttpRequest({
            method: "GET",
            url: cssUrl,
            onload: function(response) {
                if (response.status === 200) {
                    const wrappedCSS = `${CSS_MARKER}\n${response.responseText}`;
                    GM_addStyle(wrappedCSS);
                } else {
                    console.error(`custard: failed to load CSS from ${cssUrl} (status ${response.status})`);
                }
            },
            onerror: function(err) {
                console.error("custard: error fetching CSS:", err);
            }
        });
    }

    window.addEventListener('load', applyCustomStyle);
    window.addEventListener('popstate', applyCustomStyle);
    document.addEventListener('pjax:end', applyCustomStyle);

    ['pushState', 'replaceState'].forEach(fnName => {
        const original = history[fnName];
        history[fnName] = function() {
            const ret = original.apply(this, arguments);
            setTimeout(applyCustomStyle, 0);
            return ret;
        };
    });
})();