What an HTML file needs before hosting
A standalone file can include its CSS and JavaScript inline or use resources that already live on the web. The document should contain the page you want visitors to see and can be named index.html for clarity.
If the HTML points to files such as ./styles.css or ./images/hero.jpg, those files also need to be hosted. Uploading the whole project prevents the common problem where the HTML loads but its design and images are missing.
