It's a general question or dumb question you may think, but for me who are just study and wonder. You set a class in a CSS file and then use that class in an HTML file. Am I right?
But, when I tried to study a template of zurb foundation 5, I was confused.
Example: <ul class="example-orbit-content" data-orbit>
I cannot find the class example-orbit-content.
Where is this class?
Zurb Foundation's Docs have a separate stylesheets that override or add to their default foundation.min.css.
The foundation.css does not contain all of the styles they use on there site, just there default framework styles. If you want there .example.orbit.content, look for the stylesheet its styles are coming from in dev tools.