To apply CSS in HTML elements, selector and declaration block is required.
Selector is HTML elements name, id or class used to apply style.
Declaration is a block, starts with open curly brace and ends with close curly brace, which contains css properties to apply style on html element.
Multiple properties can be used to apply style, separated with a semi-colon. css property always has a value separated with a colon. property always ends with semicolon.
Multiple css properties example:
h1 {
color: blue;
text-align: center;
}where h1 is selector, open curly brace and close curly brace is declaration and color: blue; text-align: center are css properties.
Multiple css properties are used in above example, color is a property with value blue separated by a colon, and one more property text-align: center is there.