Here is a link to another HTML5 demo – a Venn Pie Chart showing solutions for simple Bayesian problems.
The point I am trying to make is that solution is the ratio between the areas of the silver and gray sectors, or, rather, lengths of corresponding arcs.
Here is a demo of a Venn Pie Chart applet, built with HTML5.
Of course, old browsers that do not support HTML5 will not show anything.
The file is hosted at dropbox.com using the “enable public folder trick” (just click https://www.dropbox.com/enable_public_folder).