Page 144 - CSS

Chapter 21: Custom Properties (Variables)

Introduction

CSS Variables allow authors to create reusable values which can be used throughout a CSS
document.

For example, it's common in CSS to reuse a single color throughout a document. Prior to CSS
Variables this would mean reusing the same color value many times throughout a document. With
CSS Variables the color value can be assigned to a variable and referenced in multiple places.
This makes changing values easier and is more semantic than using traditional CSS values.

Syntax

• :root {} /* pseudo-class that allows for more global definition of variables */
• --variable-name: value; /* define variable */
• var(--variable-name, default-value) /* use defined variable with default value fallback */

Remarks

CSS Variables are currently considered an experimental technology.

BROWSER SUPPORT / COMPATIBILITY

Firefox: Version 31+ (Enabled by default)

More info from Mozilla

Chrome: Version 49+ (Enabled by default).

"This feature can be enabled in Chrome Version 48 for testing by enabling the experimental Web
Platform feature. Enter chrome://flags/ in your Chrome address bar to access this setting."

IE: Not Supported.

Edge: Under Development

Safari: Version 9.1+

Examples

Variable Color

:root {

https://riptutorial.com/ 122