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-colorbackground-imagebackground-repeatbackground-attachmentbackground-positionbackground(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 */
}
