Simple sliding doors button techniques done in CSS for scalable buttons.

Create a text file called slogans.txt with permissions that it can be read by the server. Put each slogan on a different line, e.g.:

Building websites since before there was a web.
The internet is for lovers.

The below code will give you the X, Y coordinates of a mouse click within a given box. Removing all the stuff about the offset, you can easily get the X, Y coordinates of the click relative to the browser window.