CSS Backgrounds
The CSS background properties are used to add background effects for elements.
CSS background-color
The background-color property specifies the background color of an element.
Example
<!DOCTYPE html>
<html>
<head>
<style>
body {
background-color: lightblue;
}
</style>
</head>
<body>
<h1>Hello World!</h1>
<p>This page has a light blue background color!</p>
</body>
</html>
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)”
Look at CSS Color Values for a complete list of possible color values.
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:
<!DOCTYPE html>
<html>
<head>
<style>
h1 {
background-color: green;
}
div {
background-color: lightblue;
}
p {
background-color: yellow;
}
</style>
</head>
<body>
<h1>CSS background-color example!</h1>
<div>
This is a text inside a div element.
<p>This paragraph has its own background color.</p>
We are still in the div element.
</div>
</body>
</html>
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
<!DOCTYPE html>
<html>
<head>
<style>
div {
background-color: green;
}
div.first {
opacity: 0.1;
}
div.second {
opacity: 0.3;
}
div.third {
opacity: 0.6;
}
</style>
</head>
<body>
<h1>Transparent Boxes</h1>
<p>When using the opacity property to add transparency to the background of an element, all of its child elements become transparent as well. This can make the text inside a fully transparent element hard to read:</p>
<div>
<h1>opacity 0.1</h1>
</div>
<div>
<h1>opacity 0.3</h1>
</div>
<div>
<h1>opacity 0.6</h1>
</div>
<div>
<h1>opacity 1 (default)</h1>
</div>
</body>
</html>
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).
Tip: You will learn more about RGBA Colors in our CSS Colors Chapter.
Example
<!DOCTYPE html>
<html>
<head>
<style>
div {
background: rgb(0, 128, 0);
}
div.first {
background: rgba(0, 128, 0, 0.1);
}
div.second {
background: rgba(0, 128, 0, 0.3);
}
div.third {
background: rgba(0, 128, 0, 0.6);
}
</style>
</head>
<body>
<h1>Transparent Boxes 2</h1>
<p>Result with opacity:</p>
<div style=”opacity:0.1;”>
<h1>10% opacity</h1>
</div>
<div style=”opacity:0.3;”>
<h1>30% opacity</h1>
</div>
<div style=”opacity:0.6;”>
<h1>60% opacity</h1>
</div>
<div>
<h1>opacity 1</h1>
</div>
<p>Result with rgba():</p>
<div>
<h1>10% opacity</h1>
</div>
<div>
<h1>30% opacity</h1>
</div>
<div>
<h1>60% opacity</h1>
</div>
<div>
<h1>default</h1>
</div>
<p>Notice how the text gets transparent as well as the background color when using the opacity property.</p>
</body>
</html>