<html> <head> <style type="text/css" id="myStyle"> .rule1 { font-family:Times New Roman; font-size:18pt; color:blue; } .rule2 { font-family:Verdana; color:red; } .rule3 { color:red; } </style></head> <body> <button onclick="alert(document.styleSheets(0).rules.length);"> Get number of rules </button>