Replace Github code block css with the style Slack uses. (Use TamperMonkey on Chrome or GreaseMonkey on Firefox)

code-style.js

// ==UserScript==
// @name       Replace Github code style
// @namespace  https://www.derivatived.com/
// @version    0.1
// @description  Remove all Pulse stories from LinkedIn news feed
// @match      https://github.com/*
// @copyright  2014, Praful Mathur
// ==/UserScript==

function addGlobalStyle(css) {
    var head, style;
    head = document.getElementsByTagName('head')[0];
    if (!head) { return; }
    style = document.createElement('style');
    style.type = 'text/css';
    style.innerHTML = css;
    head.appendChild(style);
}

var code_css = ".markdown-body code, .markdown-body tt { \
        color: #c25; \
        background-color: #f7f7f9; \
        border: 1px solid #e1e1e8; \
        border-radius: 3px; \
    }"
addGlobalStyle(code_css);