In its most basic form, CSS looks like this.
The description is as follows.
The selector points to the HTML element you want to style.
The declaration block contains one or more declarations separated by semicolons.
Each declaration includes a CSS property name and a value, separated by a colon.
End CSS declarations with a semicolon
Surround declaration blocks by curly braces
source - w3schools.com
For example, you might have a style that looks like this.
body {
bgcolor: pink;
text-align: center;
}