I don't know if it works in the designer. I found 2 pages that didn't work in the designer. I was able to fix one of them, but not the other. But they still work fine at runtime.
I explained this before - it's due to a bug in Visual Studio. You don't need to edit them in the designer - you can just edit them in the HTML window.
You're going to be in trouble if you try to do much in the designer with this application. The code is a mix of HTML tags and ASP tags, and you can't see all of the important elements in the designer.
I have trouble explaining this to some co-workers, too. You have to understand that Windows apps lean heavily on the Form Designer, but web apps of any complexity require you to work in the HTML Window in many cases. ThePhile uses flow layout, and not grid layout. The tags are hand designed in many cases.
I think you'd like it better if you used Grid layout and did most of your .aspx work in the Forms Designer. This is a valid option, but users with older browsers won't like the way your site looks if you do it this way. You should download Firefox and check out how bad Grid forms look in it. Then look at ThePhile in Firefox - you'll see that ThePhile looks great in it! That's because of the way they hand-designed the tags in the .aspx files. I can see that they spent a lot of time on it - especially in the Forums.
By the way, some of the .aspx pages in ThePhile are actually set to Grid Layout by mistake. You should change them all to Flow layout.
Do some web searches for "flow layout" and "grid layout" for more info. Or, read the Amit Kalani book :-)