Learn CSS #6

Posted on by Apostube

CSS Backgrounds

The CSS background properties are used to add background effects for elements.

In these chapters, you will learn about the following CSS background properties:

  • background-color
  • background-image
  • background-repeat
  • background-attachment
  • background-position
  • background (shorthand property)

CSS background-color

The background-color property specifies the background color of an element.

Example

The background color of a page is set like this:

body {
  background-color: lightblue;
}

With CSS, a color is most often specified by:

  • a valid color name – like “red”
  • a HEX value – like “#ff0000”
  • an RGB value – like “rgb(255,0,0)”

Other Elements

You can set the background color for any HTML elements:

Example

Here, the <h1>, <p>, and <div> elements will have different background colors:

h1 {
  background-color: green;
}

div {
  background-color: lightblue;
}

p {
  background-color: yellow;
}

Opacity / Transparency

The opacity property specifies the opacity/transparency of an element. It can take a value from 0.0 – 1.0. The lower value, the more transparent:

opacity 1

opacity 0.6

opacity 0.3

opacity 0.1

Example

div {
  background-color: green;
  opacity: 0.3;
}

Note: When using the opacity property to add transparency to the background of an element, all of its child elements inherit the same transparency. This can make the text inside a fully transparent element hard to read.

Transparency using RGBA

If you do not want to apply opacity to child elements, like in our example above, use RGBA color values. The following example sets the opacity for the background color and not the text:

100% opacity

60% opacity

30% opacity

10% opacity

An RGBA color value is specified with: rgba(red, green, blue, alpha). The alpha parameter is a number between 0.0 (fully transparent) and 1.0 (fully opaque).

Example

div {
  background: rgba(0, 128, 0, 0.3) /* Green background with 30% opacity */
}

Apostube

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