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:
EXAMPLE:
div {
background-color: green;
opacity: 0.3;
}
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:
You learned from our CSS Colors Chapter, that you can use RGB as a color value. In addition to RGB, you can use an RGB color value with an alpha channel (RGBA) - which specifies the opacity for a color.
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 */
}