Movable Type 3's default template is different from MT2.x. Well, not hugely different, but different enough to break all the stylesheets here. Of course, it is possible to code CSS to be used in both MT2 and MT3, but it is restrictive and quite a bit of work. MT3 includes another div id="center" around the content and sidebar, so it is possible to do more fancy styles around it. - Scott Yang
One wonders how to describe the new default styles.
The new styles suck...hard. They are all the same except for color. Even Blogger has better layouts. Again, they want us to do all the work, and pay for the privilege. - Laura McMasters
I am really surprised at what a giant step backward these are.