GmailBiggerText Tampermonkey user script.

GmailBiggerText-Tampermonkey.js

// ==UserScript==
// @name           Gmail Bigger Text
// @namespace      https://ahmetardal.com
// @homepageURL    https://gist.github.com/ahmetardal/27d2a4d5f213c7d869e64a01f8779351
// @description    Bigger text for Gmail
// @author         Ahmet Ardal
// @version        1.0
// @include        https://mail.google.com/*
// @include        https://*.mail.google.com/*
// @grant          GM_addStyle
// ==/UserScript==

var css = `
    .gmail_default, div, span, p, a { font-size: medium !important; }
    .ii, .Ak { font-size: medium !important; }
    .editable { font-size: medium !important; }
`;

if (typeof GM_addStyle != "undefined") {
    GM_addStyle(css);
} else if (typeof addStyle != "undefined") {
    addStyle(css);
} else {
    var heads = document.getElementsByTagName("head");
    if (heads.length > 0) {
        var node = document.createElement("style");
        node.type = "text/css";
        node.appendChild(document.createTextNode(css));
        heads[0].appendChild(node);
    }
}