There is some modification of the HTML and CSS files, but mainly a Javascript file was created with the objective to build the app's functionality from a static project to an interactive one while maintaining responsiveness accross devices.
The objective of the Landing Page project is to add functionality to a static webpage: add a navigation bar with pointers that highlight sectional links upon hovering, that smoothly scroll into sections of the webpage upon clicking, and enable events over a section to activate its css styling on that particular active section.
Furthermore, placing additional sections to the webpage dynamically extends the functionality of the website features described above.
Udacity provided some HTML and CSS styling to display a static version of the Landing Page project.