The output in the frontend is controlled by Typoscript. This video gives you an overview of the most important Typoscript files.
All typoscripts used are available in separate, external files. These files are integrated into the main template on the "Home" page.
The Typoscript files can be found in the directory fileadmin/jweilandnet_musterprojekt/Resources/Typoscript/
The display of the sample project is controlled via two CSS files: