The starting place for this page was the game, Lights Out, which was also the basis for my Amiga game FlipGrid. It was an experiment to see how small I could get a web page. The final version was 1.2K.
During development, I read about the Sylloge competition to design a site in 5K. I expanded the entry to feature other mathematical puzzles and curiosities. Each was presented in its' own frame, divided according to the golden ratio, appropriately enough.
UPDATE: The code got lost when my old site was stolen :( I will try and find a backup one day!