CSS3 RGBa Color – Semi-transparent Color

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This is an RGB color with a fourth parameter (a number) which is the alpha transparency channel.

rgba(_red_, _green_, _blue_, _transparency_);

Semi-transparent RGBa colors can be applied anywhere in CSS where a color is commonly used. Just to mention a few: borders, shadows or gradients.

A Comparison With opacity

opacity: 0.5 will make an element and all its children semi-transparent.

RGBa is a color that can be applied to any element without influencing the rest of it (e.g. its children). In other words, you can use it for background color like this: background: rgba(20%, 100%, 20%, .5).

Take a look at cdpn.io/e/HrBsD.

Browser Support

All browsers except IE8 and older versions have no problem with rendering RGBa. However, by using a defined fallback, you can respectfully deal with “the elderly”.

color: rgb(128, 0, 0);
color: rgba(255, 0, 0, 0.5);

This fallback will be rendered by modern browsers as a red color with a 50% transparency. IE8 will render it as a dark shade of red. A fallback color must be defined with respect to the background color, which is black in this case.

You can alternatively use CSS3Pie.




Content

Introduction

Introduction

On today’s frontend UI development

UI development transformations

Tools, technologies and workflows

Fallback strategies

CSS3 reference guide

Introduction

Text properties

Background properties

Border properties

Box properties

Media Queries

CSS transforms

CSS animations

CSS3 Layout

Another CSS3 Properties

Non-standard properties

End

End

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