In CSS we have five different ways of choosing
a color. The first two are the same as in HTML: named
and hexadecimal colors. We also have a short hexadecimal notation,
which can be converted to hexadecimal by duplicating each digit.
Then we have a functional notation, where each value can be between 0 and 255 or a percentage. Here’s an example using all notations to create
the color red. So, if we want to specify a color we can use either one of these notations.