Although the HTML5 & CSS3 specifications are still in active development, web browsers have already begun progressively adding support for most elements in newer versions.
Implementation by Mozilla Firefox Google Chrome, Internet Explorer, Opera, Safari and other web browsers has been irregular, making cross-platform compatibility challenging. Through the use of clever open source software such as Modernizr, we can take advantage of emerging technologies for the majority, while still retaining a good user experience for older web browsers.