Final answer:
HTML files for a multi-page static website are typically placed in the root directory, while CSS files are stored separately in a 'css' folder for organizational clarity.
Step-by-step explanation:
When building a multi-page static website, HTML files are typically stored in the root directory of the website. However, some developers may choose to organize files into a dedicated folder if it makes the project clearer or easier to navigate, especially as the site grows in complexity. It's important to note that storing HTML files in the CSS folder would be improper as CSS files should be in their own dedicated folder (often named 'css') to maintain organization and separation of content (HTML) from presentation (CSS).