A CSS comprises of style rules that are interpreted by the browser and then applied to the corresponding elements in your document. A style rule is made of three parts: a selector, a property, and a value. CSS selectors are used to find HTML elements based on their element name as: id, class, attribute, and more.

The element selector selects elements based on the element name.
You can select all <h1> elements on a page like this (all elements will be left-aligned, with a green text color).

Example: The id selector is used to select one unique element! To select an element with a specific id, write a hash (#) character, followed by the id of the element. The style rule will be applied to the HTML element with id="unika", (in this case, #unika element will be height: 200px with a green background-color and 14 px font-size):

Example: All the elements having that class will be formatted according to the defined rule. To select elements with a specific class, write a dot . character, followed by the name of the class. The style rule will be applied to the HTML element with class="box1", (in this case, box1 element will be height: 200px with a green background-color and 14 px font-size):

Example: You can apply a style to many selectors how you like. Just separate the selectors with a comma as in the examples above.

Example:
OK, so you've now learned about the CSS style syntax, but how do you incorporate this syntax into your website? The next lesson will show you how to incorporate CSS into your HTML webpage.


Syntax of CSS, How to Code CSS, Basic CSS
Basic Syntax of CSS - How to Code CSS - css tutorial