How can I be sure that my web site can be viewed in smatphones (with different resolutions and screen's size) without any problem.
Is there a way to convert the couple html/css of a classic web site to be compatible everywhere.
Best regards.
I use http://mite.keynote.com/ to help test websites on mobiles that I don't have physically available. It's not perfect, but it's about the best testing suite I've seen and will definitely give you an idea of whether or not your design will work.
As for the actual design methodology, just make sure you don't specify anything in pixels or points, all dimensions should be specified with em's (or ex, etc) or percentages. From there, it's just a matter or trying things to see if they work.