CSS Image Opacity (Transparent Image)
The opacity
property specifies the opacity/transparency of an element.
Transparent Image
The opacity
property can take a value from 0.0 - 1.0. The lower the value, the more transparent:

opacity 0.2

opacity 0.5

opacity 1
(default)
Example
opacity: 0.5;
}
Transparent Hover Effect
The opacity
property is often used together with the :hover
selector to change the opacity on mouse-over:



Example
opacity: 0.5;
}
img:hover {
opacity: 1.0;
}
Example explained
The first CSS block is similar to the code in Example 1. In addition, we have added what should happen when a user hovers over one of the images. In this case we want the image to NOT be transparent when the user hovers over it. The CSS for this is opacity:1;
.
When the mouse pointer moves away from the image, the image will be transparent again.
An example of reversed hover effect:



Example
opacity: 0.5;
}
Transparent Box
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:
opacity 1
opacity 0.6
opacity 0.3
opacity 0.1
Example
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:
100% opacity
60% opacity
30% opacity
10% opacity
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
background: rgba(0, 0, 220, 0.3) /* Blue background with 30% opacity */
}
Text in Transparent Box
This is some text that is placed in the transparent box.
Example
<head>
<style>
div.background {
background: url(smiley.jpg) repeat;
border: 2px solid #0054ff;
}
div.transbox {
margin: 30px;
background-color: #ffffff;
border: 1px solid #0054ff;
opacity: 0.6;
}
div.transbox p {
margin: 5%;
font-weight: bold;
color: #000000;
}
</style>
</head>
<body>
<div class="background">
<div class="transbox">
<p>This is some text that is placed in the transparent box.</p>
</div>
</div>
</body>
</html>
Example explained
First, we create a <div> element (class="background") with a background image, and a border.
Then we create another <div> (class="transbox") inside the first <div>.
The <div class="transbox"> have a background color, and a border - the div is transparent. It also has margins for spacing between outer <div> and inner <div>.
Inside the transparent <div>, we add some text inside a <p> element.
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