Hello.

There are 3 parts in Smart search result web part properties the design depends on. "Transformation name," "Pager design" and "Web part container". When you see code of your transformation or code of particular templates for your pager settings, you can see what classes are used there. Also, some classes used for search page are defined in site's stylesheet in Site Manager / Development / CSS stylesheets section. Feel free to open particular stylesheet and search for "search" word. Thank you.

Best Regards,
Radek Macalik