Fonts and Size
What is the cleanest looking font and what is the best font size?
Sans-serif fonts look cleaner than serif fonts as they don't have "the curly bits" at the ends of letter shapes. However, it is thought that serif fonts are easier to read. As to font size it is best to use a size that suits the viewers of your page. For example older people have poorer eyesight than younger people, therefore need a bigger font size. For example 19 pixels. Browsers usually have a default font size of 16 pixels and a default serif font family. You can play around with the CSS in this repl: https://repl.it/@malvoliothegood/fonts#style.css
@HahaYes It depends on what the site is for. Look at similar sites and see what fonts are used. You can highlight some text, right-click and choose "Inspect Element", or similar wording - depends on the browser. The browser's developer tools will open and in the CSS panel you will be able to inspect the font-family, font-size and color, and so on...
The best font is obviously Arial. A font size 11 is the minimum requirement, but like 15 is used too.
This is all based on user-preference.
Mark as correct answer!