Method: 1. Add the "background-color:rgba(R,G,B,A)" style to the element to set the color transparency; 2. Add the "opacity:transparent value;" style to the element to set it Transparency; 3. Set the "filter:opacity(%);" style to the image to increase transparency.
The operating environment of this tutorial: Windows 7 system, CSS3&&HTML5 version, Dell G3 computer.
There are three ways to set transparency in css:
rgba()opacityAttributesfilter:opacity(%)
Method 1: rgba () function
rgba() function can set the color transparency. The syntax is as follows:
RGBA(R,G,B,A)
Value:
R: Red value . Positive integer | Percent
G: Green value. Positive integer | Percent
B: Blue value. Positive integer | Percent
A: Alpha transparency. The value is between 0~1.
For example: rgba(255,0,0,0.5)Translucent red
rgba() can simply set the color transparency. This has many applications in page layout. For example: make the background transparent, but the text above is opaque.
Example:
background-color:rgba(0,152,50,0.7);// -->70%的不透明度 background-color:transparent;支持完全透明
(Learning video sharing: css video tutorial)
Method 2 : Use the opacity attribute
In CSS3, an opacity attribute is added. You can use this attribute to set the transparency of the element. The opacity attribute is inherited and will make all elements in the container transparent;
Syntax:
opacity: value ;
value: Specifies opacity, starting from 0.0 (fully transparent) to 1.0 (fully opaque).
Example:
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>opactity</title>
<style>
.box1{
position:relative;
width:200px;height:200px;
background-color: #00f;
}
.box2{
position:absolute;
top:80px;
left:80px;
width:200px;
height:200px;
background-color:#0f0;
}
.box3{
position:relative;
width:200px;
height:200px;
background-color:#f00;
z-index:1;
}
</style>
</head>
<body>
<div></div>
<div></div>
<div></div>
</body>
</html>
The effect of setting transparency
.box1{
position:relative;
width:200px;height:200px;
background-color: #00f;
z-index:10;
opacity:0.5;
}
.box2{
position:absolute;
top:80px;
left:80px;
width:200px;
height:200px;
background-color:#0f0;
z-index:5;
opacity:0.5;
}
.box3{
position:relative;
width:200px;
height:200px;
background-color:#f00;
z-index:1;
opacity:0.5;
}Performance effect:
Method 3: Set filter:opacity(%)Style to set the transparency of the image
The filter attribute is to apply the filter effect CSS method for elements on the web page (mainly images); you can set the opacity effect of the image by setting the opacity() value. 0% opacity means the element is completely transparent, and if the opacity is 100%, it means the original image.
Grammar:
filter: opacity(%);
Example:
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<style>
.opacity1 {
opacity: 0.5;
filter: none;
}
.opacity2 {
opacity: 0.2;
filter: none;
}
</style>
</head>
<body>
<div>
正常图片:<br /><br />
<img src="/static/imghwm/default1.png" data-src="1.jpg" class="lazy" style="max-width:90%" / alt="How to set transparency in css using three methods" ></div><br />
<div>
设置透明度的图片：<br /><br />
<img class="opacity1 lazy" src="/static/imghwm/default1.png" data-src="1.jpg" style="max-width:90%" / alt="How to set transparency in css using three methods" >
<img class="opacity2 lazy" src="/static/imghwm/default1.png" data-src="1.jpg" style="max-width:90%" / alt="How to set transparency in css using three methods" >
</div>
</body>
</html>Rendering:
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