I created a new ASP.NET-MVC 5 project and added the JQuery UI NUGET package.
I'm trying to follow the tabs example show in the JQuery website and I can't fugure out why my dialog looks like this:

and the dialog in the example looks like this (look at the buttons):

The HTML is exactly the same as in the website.
I tried to look for CSS and JS errors but couldn't find any.
This happens both in FireFox and in IE9.