The CSS can be found on Google’s CDN. I’ve used it in a page or two. Here’s some CSS link tags.
<link rel="stylesheet" type="text/css" href="http://ajax.googleapis.com/ajax/libs/dojo/1.4/dojo/resources/dojo.css">
<link rel="stylesheet" type="text/css" href="http://ajax.googleapis.com/ajax/libs/dojo/1.4/dijit/themes/tundra/tundra.css">
Much like the libraries, you can pick a more or less specific version in the URL, so this will grab the latest in the 1.4.x chain.
UPDATED [19/May/2016]:-
Update version – 1.10.4
<link rel="stylesheet" type="text/css" href="http://ajax.googleapis.com/ajax/libs/dojo/1.10.4/dojo/resources/dojo.css">
<link rel="stylesheet" type="text/css" href="http://ajax.googleapis.com/ajax/libs/dojo/1.10.4/dijit/themes/tundra/tundra.css">