https://www.freecodecamp.org/learn/responsive-web-design/basic-css/use-hex-code-for-specific-colors
Use Hex Code for Specific Colors
Did you know there are other ways to represent colors in CSS? One of these ways is called hexadecimal code, or hex code for short.
We usually use decimals, or base 10 numbers, which use the symbols 0 to 9 for each digit. Hexadecimals (or hex) are base 16 numbers. This means it uses sixteen distinct symbols. Like decimals, the symbols 0-9 represent the values zero to nine. Then A,B,C,D,E,F represent the values ten to fifteen. Altogether, 0 to F can represent a digit in hexadecimal, giving us 16 total possible values. You can find more information about hexadecimal numbers here.
In CSS, we can use 6 hexadecimal digits to represent colors, two each for the red (R), green (G), and blue (B) components. For example, #000000 is black and is also the lowest possible value. You can find more information about the RGB color system here.
body { color: #000000; }
TEST
Replace the word black in our body element's background-color with its hex code representation, #000000.
<style>
body {
background-color: #000000;
}
</style>