Issues with Internet Explorer, Firefox and Opera

1. Always use document.getElementById to get HTML elements. Internet Explorer supports accessing elements using the element ID directly, but Firefox and Opera do not. You can also use the shortcut function 'PF.$' instead of document.getElementById.
2. There's no innerText in Firefox. So, use PF.T(element, text) to set text content inside HTML elements.
3. CSS renders differently in Firefox, Opera and Internet Explorer, so make sure you test your flakes in all these browsers.