Instrumented the 'isElementCenteredInPage' CSS test function
Fixed rounding issues in isElementCenteredInPage()
Modified 'overlapping pixels' CSS test functions to round off fractions
Upgraded Mac Safari 6.1.5 --> 6.1.6
'Join Us' button now has rounded corners
Spiked box-shadow for 'Join Us' button
Got test of drop shadow working
Vertically centered text in button