Tampermonkey userscript to rescue your X (formerly Twitter) experience.

fuck-x.user.js

// ==UserScript==
// @name         Fuck X
// @namespace    http://tampermonkey.net/
// @version      0.1
// @description  Save your eyes while using X (formerly Twitter)
// @author       Cyandev <unixzii@gmail.com>
// @match        https://twitter.com/*
// @grant        none
// ==/UserScript==

(function() {
    'use strict';

    const mo = new MutationObserver(handleDOMMutations);
    let pendingMods = [];

    function addMod(selector, fn) {
        pendingMods.push({ selector, fn });
    }

    function runPendingMods() {
        pendingMods = pendingMods.filter(m => {
            const el = document.querySelector(m.selector);
            if (!el) {
                // The element is not ready, keep it in the queue.
                return true;
            }
            console.debug(`running mod for \`${m.selector}\``);
            try {
                m.fn(el);
            } catch {
                // An error occurred, maybe we should retry later.
                return true;
            }
            return false;
        });

        return pendingMods.length > 0;
    }

    function handleDOMMutations(records) {
        if (!records.some(r => !!r.addedNodes.length)) {
            return;
        }
        if (!runPendingMods()) {
            this.disconnect();
        }
    }

    addMod('header[role="banner"] h1>a>div>svg', (el) => {
        const replacement = '<g><path d="M23.643 4.937c-.835.37-1.732.62-2.675.733.962-.576 1.7-1.49 2.048-2.578-.9.534-1.897.922-2.958 1.13-.85-.904-2.06-1.47-3.4-1.47-2.572 0-4.658 2.086-4.658 4.66 0 .364.042.718.12 1.06-3.873-.195-7.304-2.05-9.602-4.868-.4.69-.63 1.49-.63 2.342 0 1.616.823 3.043 2.072 3.878-.764-.025-1.482-.234-2.11-.583v.06c0 2.257 1.605 4.14 3.737 4.568-.392.106-.803.162-1.227.162-.3 0-.593-.028-.877-.082.593 1.85 2.313 3.198 4.352 3.234-1.595 1.25-3.604 1.995-5.786 1.995-.376 0-.747-.022-1.112-.065 2.062 1.323 4.51 2.093 7.14 2.093 8.57 0 13.255-7.098 13.255-13.254 0-.2-.005-.402-.014-.602.91-.658 1.7-1.477 2.323-2.41z"/></g>';
        el.innerHTML = replacement;
    });
    addMod('link[rel="shortcut icon"]', (el) => {
        const origFaviconUri = '//abs.twimg.com/favicons/twitter.ico';
        el.href = origFaviconUri;
    });

    mo.observe(document, {
        childList: true,
        subtree: true,
    });
})();