1. a single sound file shall play in the background of a website (the file itself can also reside on a site different from the website, if the solution requires).
2. even if page changes or refreshes the sound shall continue to play TOTALLY UNINTERRUPTED, NO GAP/HICKUPs
3. only a very simple and a small, minimalistic interface (pause/resume), no larger than around 30px high and maybe 50px width will show on all pages and while the uninterrupted sound plays it shall be possible on all pages to pause/resume the music.
Without tricks it will of course not work anyway, that I know already. I have also some ideas how the "trick"could look like, but I am not a coder, hence I let you make the first "expert suggestion" before I may add mine for you consideration... ;)