Too Long; Didn't Read
An HTML document can be filled 100% in width but not in height, otherwise, you wouldn't be able to scroll up or down and the page would be limited in vertical space. If you don't know how to create HTML documents and to apply styling to its elements, please go to freecodecamp.org and complete the basic tutorials. There are 3 main things you should be aware of while learning HTML and CSS: Filling the body of the HTML document, from left to right, from top to bottom. Knowing the 2 main things I mentioned before will make it easier for any way you want to display or position elements on a web page.