Change Github Font Family

change-github-font-family.user.js

// ==UserScript==
// @name               Change Github Font Family
// @name:zh-CN         Github网站字体切换
// @icon               https://github.githubassets.com/favicons/favicon.png
// @version            0.0.3
// @description        custom github font family
// @description:zh-CN  切换Github等网站的字体
// @namespace          https://gist.github.com/hungtcs
// @author             鸿则<hungtcs@outlook.com>
// @homepage           https://gist.github.com/hungtcs/819a64fa9e6bfa37ce391f29765acfa3
// @match              https://github.com/**
// @match              https://gist.github.com/**
// @match              https://stackblitz.com/edit/**
// @run-at             document-start
// @updateURL          https://gist.github.com/hungtcs/819a64fa9e6bfa37ce391f29765acfa3/raw/522377a3039e141e8fe70725b0bd55ad0f71e8d9/change-github-font-family.user.js
// @downloadURL        https://gist.github.com/hungtcs/819a64fa9e6bfa37ce391f29765acfa3/raw/522377a3039e141e8fe70725b0bd55ad0f71e8d9/change-github-font-family.user.js
// @grant              none
// ==/UserScript==

(function() {
  'use strict';

  const href = window.location.href;
  const fontFamilies = ['Droid Sans Mono for Powerline', 'monospace'].join(',');

  const styleElement = document.createElement('style');
  document.head.appendChild(styleElement);

  switch(true) {
    case /stackblitz\.com\/edit/.test(href): {
      styleElement.innerHTML = `.view-lines { font-family: ${ fontFamilies } !important; }`;
      break;
    }
    case /github\.com/.test(href): {
      styleElement.innerHTML = `
        .blob-code-inner { font-family: ${ fontFamilies } !important; }
        .CodeMirror pre { font-family: ${ fontFamilies } !important; }
        .previewable-comment-form textarea, .markdown-body pre, .markdown-body code { font-family: ${ fontFamilies } !important; }
      `;
      break;
    }
    default: {
      break;
    }
  }

})();