add_underlines_to_keyboard_in_keybr.userscript.js

// ==UserScript==
// @name     Add underlines to keyboard in keybr
// @version  1
// @match    *://keybr.com/
// @match    *://keybr.com/*
// @match    *://www.keybr.com/
// @match    *://www.keybr.com/*
// @grant    none
// ==/UserScript==

window.addEventListener('load', function() {
    addGlobalStyle("*[data-key='KeyF'], *[data-key='KeyJ'] { text-decoration: underline; }");
}, false);


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);
}