CSS enables us to define many many rules for fonts, colors, sizes, positions, opacity, etc.
If you look for a specific rule, a good entry point is the w3school website.
In the following, we will see some basic rules so you can play with CSS.
text-align: center; (or left, right, ...)
text-decoration: none; (or underline, overline, ...)
text-transform: uppercase; (or lowercase, smallcaps, ...)
font-style: normal; (or italic, oblique, ...)