Where are the styles for sections one, two, etc?

I am using this template (temporarily) loaded on to my site in its original form.http://posweyb.net/Spatial/index.html

I understand that the ‘section’ element is in the user agent style sheet. What I want to know is where the ids are stored. For instance:
<section id="two" class="wrapper style2 special</section>

The ID is not used for styling, I guess it’s there as a fragment ID for linking.
The class style2 appears to be used to style the second section. This can easily be seen using a browser’s inspect tools.