


Solution to the cascading order problem caused by the opacity attribute of CSS3
This article mainly introduces the method to solve the cascading order problem caused by the opacityproperty of CSS3. It mainly focuses on the problem that layers with an opacity property value less than 1 will cover other layers. It needs to Friends can refer to
In a recent work, when using the opacity attribute to achieve overall transparency of the page, a problem was discovered. If two layers overlap, the layer with the opacity attribute and the attribute value less than 1 will overwrite the subsequent layer. So I did an experiment to verify the level of opacity.
The cascading rule in web pages is like this: If neither layer has definition position attribute is absolute or relative attribute, which layer's HTML code is placed behind , which layer is displayed on top. If the position attribute is specified and the z-index attribute is set, the one with the larger value will be on top.
Found the problem
For ordinary layers that do not have z-index activated, if that layer uses an opacity attribute with an attribute value less than 1, which layer will shown above. Let's make a demo. The code is as follows:
<!DOCTYPE html> <html> <head> <title>带有 opacity 的层叠问题</title> <style> html{padding:40px;} .dd{width:100px;height:100px;} a{background:red;} b{background:blue;margin-left:20px;margin-top:-80px;} c{background:green;margin-left:40px;margin-top:-80px;} </style> </head> <body> <p id=”a”></p> <p id=”b”></p> <p id=”c”></p> </body> </html>
After saving it as an html file and opening it, you can see the normal order
At this time, we are# a plus attribute opacity: 0.9 The magic happens, it covers the other two layers
Only when another layer (for example: #c) is also set to a value less than 1 After the opacity value (for example: 0.8), the following #c can install normal rules to cover #a.
In this way, a layer with an opacity attribute less than 1 is added, raising it to a higher level. As for the scientific principles inside, I haven't figured it out, maybe it's a small bug. But sometimes this is something we don't want to happen.
Solution to the problem
So how to solve this problem? As mentioned before, under normal circumstances, the layer with position and z-index specified has a higher level than the ordinary layer. So how does the layer with opacity specified compare with the layer with position specified? Let's add position: relative to #b and see. The style code at this time is as follows:
#a{background:red;opacity:0.9;} b{background:blue;margin-left:20px;margin-top:-80px;position:relative;} c{background:green;margin-left:40px;margin-top:-80px;opacity:0.8;}
After saving and refreshing, you will see the effect like this:
In other words, after using the relative position attribute on a layer, the level can be the same as the opacity. After that, the cascading display will be performed according to the normal order (in the subsequent experiments, I also tested the absolute attribute value. The result behaves the same as the relative attribute value). When we cancel the opacity attribute of #c, we can see that #c is ranked at the bottom.
It’s not over yet, I just activated the position: relative attribute for #b before, and I haven’t used z-index yet. We set the z-index of #b (for example: 100). Obviously, #b becomes the top level.
Conclusion:
The layer using the position attribute value of absolute and relative will be higher than the ordinary layer level. The layer using the opacity attribute less than 1 is also higher than the ordinary layer and is the same layer as the layer with the specified position. However, it does not support the z-index attribute, so the layer with the specified position can use the z-index attribute to cover the band. Layers with an opacity property less than 1.
The above is the detailed content of Solution to the cascading order problem caused by the opacity attribute of CSS3. For more information, please follow other related articles on the PHP Chinese website!

Hot AI Tools

Undresser.AI Undress
AI-powered app for creating realistic nude photos

AI Clothes Remover
Online AI tool for removing clothes from photos.

Undress AI Tool
Undress images for free

Clothoff.io
AI clothes remover

AI Hentai Generator
Generate AI Hentai for free.

Hot Article

Hot Tools

Notepad++7.3.1
Easy-to-use and free code editor

SublimeText3 Chinese version
Chinese version, very easy to use

Zend Studio 13.0.1
Powerful PHP integrated development environment

Dreamweaver CS6
Visual web development tools

SublimeText3 Mac version
God-level code editing software (SublimeText3)

Hot Topics

How to achieve wave effect with pure CSS3? This article will introduce to you how to use SVG and CSS animation to create wave effects. I hope it will be helpful to you!

This article will show you how to use CSS to easily realize various weird-shaped buttons that appear frequently. I hope it will be helpful to you!

Two methods: 1. Using the display attribute, just add the "display:none;" style to the element. 2. Use the position and top attributes to set the absolute positioning of the element to hide the element. Just add the "position:absolute;top:-9999px;" style to the element.

In CSS, you can use the border-image attribute to achieve a lace border. The border-image attribute can use images to create borders, that is, add a background image to the border. You only need to specify the background image as a lace style; the syntax "border-image: url (image path) offsets the image border width inward. Whether outset is repeated;".

How to create text carousel and image carousel? The first thing everyone thinks of is whether to use js. In fact, text carousel and image carousel can also be realized using pure CSS. Let’s take a look at the implementation method. I hope it will be helpful to everyone!

Adaptive layout, also known as "responsive layout", refers to a web page layout that can automatically recognize the screen width and make corresponding adjustments; such a web page can be compatible with multiple different terminals instead of making a specific version for each terminal. . Adaptive layout was born to solve the problem of mobile web browsing, and can provide a good user experience for users using different terminals.

Implementation method: 1. Use the ":active" selector to select the state of the mouse click on the picture; 2. Use the transform attribute and scale() function to achieve the picture magnification effect, the syntax "img:active {transform: scale(x-axis magnification, y Axis magnification);}".

The animation effect in css3 has deformation; you can use "animation: animation attribute @keyframes ..{..{transform: transformation attribute}}" to achieve deformation animation effect. The animation attribute is used to set the animation style, and the transform attribute is used to set the deformation style. .
