Unless otherwise agreed as a part of the project price, like most web developers, we code for the latest version of all browsers and the version that came before that whilst allowing wherever possible for graceful degradation on browsers which are out of date . For all other versions, we take part in Browser-Update.org which displays a short message at the top of the screen recommending that the user upgrade. If we tried to code for every version ever issued of a browser, it would be pretty much impossible to deliver within a reasonable timeline and the cost per site would be phenomenal!