I'm a designer of many fields: Game, Product and UX/UI. I'm specialising in HTML5 & CSS3 in it's purest form.
I believe in starting with a website that complies to the latest excepted standards and then gracefully degrading to older browsers.
I dont believe in starting with hacks generally involving javascript to make controls or enable new features. This leads to flabby sites that will not provide the optimum experience in compliant browsers.