Userscript to restore the red arXiv header. Install with Tampermonkey: https://www.tampermonkey.net/.

arxiv_red_header.user.js

// ==UserScript==
// @name         arXiv red header
// @namespace    https://arxiv.org/
// @version      1.2
// @description  Revert the June 2026 black arXiv header to the classic red (#b31b1b) with the old white logo
// @match        https://arxiv.org/*
// @match        https://*.arxiv.org/*
// @run-at       document-start
// @grant        GM_addStyle
// ==/UserScript==

(function () {
  "use strict";

  const css = `
    .ds-site-header {
      background: #b31b1b !important;
    }
    .ds-site-header-nav a,
    .ds-site-header-nav a:visited,
    .ds-site-header-nav button,
    .ds-site-header-nav-toggle {
      color: #f2d5d5 !important;
    }
    .ds-site-header-nav a:hover,
    .ds-site-header-nav button:hover,
    .ds-site-header-nav-toggle:hover {
      background: #8f1414 !important;
      color: #ffffff !important;
    }
    .ds-site-header-login {
      color: #ffffff !important;
    }
    .ds-site-header-divider {
      background: rgba(255, 255, 255, 0.35) !important;
    }
    @media (max-width: 599px) {
      .ds-site-header.is-collapsible .ds-site-header-nav {
        background: #b31b1b !important;
        border-top-color: rgba(255, 255, 255, 0.3) !important;
      }
      .ds-site-header.is-collapsible .ds-site-header-nav a,
      .ds-site-header.is-collapsible .ds-site-header-nav button {
        border-bottom-color: rgba(255, 255, 255, 0.25) !important;
      }
    }
  `;

  if (typeof GM_addStyle === "function") {
    GM_addStyle(css);
  } else {
    const style = document.createElement("style");
    style.textContent = css;
    (document.head || document.documentElement).appendChild(style);
  }

  const whiteLogo = "https://arxiv.org/static/browse/0.3.4/images/arxiv-logo-one-color-white.svg";
  function swapLogo() {
    document.querySelectorAll(".ds-site-header-logo img").forEach((img) => {
      img.src = whiteLogo;
      img.removeAttribute("srcset");
    });
  }
  if (document.readyState === "loading") {
    document.addEventListener("DOMContentLoaded", swapLogo);
  } else {
    swapLogo();
  }
})();