HTML tutorial
CSS3 tutorial
Bootstrap tutorial
JavaScript tutorial
JQuery tutorial
AngularJS tutorial
React tutorial
NodeJS tutorial
PHP tutorial
Python tutorial
Python3 tutorial
Django tutorial
Linux tutorial
Docker tutorial
Ruby tutorial
Java tutorial
C tutorial
C ++ tutorial
Perl tutorial
JSP tutorial
Lua tutorial
Scala tutorial
Go tutorial
ASP.NET tutorial
C # tutorial
The opacity property specifies the opacity/transparency of an element
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)
img {
opacity: 0.5;
}
The opacity
property is often used together with the :hover
selector to change the opacity on mouse-over:
img {
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:
img:hover {
opacity: 0.5;
}
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
div {
opacity: 0.3;
}
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 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).
div {
background: rgba(76, 175, 80, 0.3) /* Green background with 30%
opacity */
}
This is some text that is placed in the transparent box.
<html>
<head>
<style>
div.background {
background: url(klematis.jpg) repeat;
border: 2px solid black;
}
div.transbox {
margin: 30px;
background-color: #ffffff;
border: 1px solid black;
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>
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.
Inside the transparent <div>, we add some text inside a <p> element.
Use CSS to set the transparency of the image to 50%.
<style> img { : ; } </style> <body> <img src="klematis.jpg" width="150" height="113"> </body>