Quote: "And buttons should be graphics. Because you will need a lots of knowledge to make your complicated button looks exactly the same in all browsers."
If you are using actual <button> or <input type="button"> elements yeah, some browsers pretty much ignore most/all styling on these kinds of elements (glares at Safari)
You can go with styled div's, but you will need to handle click events in javascript, which means users will need to have javascript enabled. Non-trivial pages/web apps will need plenty of javascript anyways so this isn't much of an issue, or rather you'll have bigger issues than buttons to worry about if javascript isn't running.
Anyway, SVG is great, but I still use plenty of css too