No, not anywhere else because you wouldn't be able to use the styles used in CSS Zen Garden on any other site.
I apologize if I'm not clear enough explaining this.
What happens is that CSSZG is showing you that once you have your elements and classes defined, you won't need to touch your HTML to change the look of your site. All you'd need to do is change your CSS and voila. It's the same thing with Sandbox. You don't need to touch the HTML code, only the CSS.
The same can be applied to any website that's CSS based for presentation. For instance, in the old days you'd write something like this:
<font color="#ff0000" size="2"><b>Warning, this is a hazardous place!</b></font>
The above would produce a big text in red and bold. But what if your design changed and you needed to italicize it, make it blue and not bold? then you would have to go and change these properties in the HTML code:
<font color="#0000ff" size="2"><i>Warning, this is a hazardous place!</i></font>
With CSS you don't have to do this anymore. You'd need to define a 'warning' class in your HTML and change its appearance using CSS. Example:
<div class="warning">This is a hazardous place!</div>
So, in your CSS, if you want to make this text big, bold and red you'd do something like this:
.warning{
font-size: 20pt;
color: #f00;
font-weight: bold;
}
(There is a shorthand for the above code, where you can write those attributes in one line, but I've never been good at writing the font shorthand.)
Now, if your design changes and you need to change your warning text to orange, italics, not bold and a bit smaller than before, plus you want to add a background color to it, then you'd just need to modify your class definition like so:
.warning{
font-size: 16pt;
color: #f90; /*I think this is the code for orange*/
font-style: italic;
background: #eee;
}
When you load your page, this style should be applied and you didn't even have to mess with the HTML part. Cool, isn't it? :)