CSS structure

Introduction

CSS is a language that describes the style of an HTML document. CSS describes how HTML elements should be displayed.
Elements in CSS are divided into two parts: selector and declaration.
Selector is the HTML element that you want to style. Declaration is the style that you want to apply to the selector.
Declaration is divided into two parts: property and value. Property is the style that you want to apply to the selector. Value is the value of the style that you want to apply to the selector.

Source: https://www.w3schools.com/css/img_selector.gif

For example, if you want to change the color of the text to red, you can use the color property and the value red.

<style>
	h1 {
		color: red;
	}
</style>