AJAX Calendar Extender only shows partial weekdays

The Calendar extender in my page only shows 5 days in a week, instead
of a full 7 days. There is no parameters controlling this behavior.
After some investigation I found that's because I have defined padding
in my stylesheet for TD:

TD {padding-left:5px;padding-right:5px;}

Generally it's not a good idea to change the general TD style,
especially third-party control will be used. I put the padding in my
own table class then problem solved!