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How to adjust the priority of css style cascading

PHPzOriginal: 2024-02-23 14:15:031288browse

Methods for CSS style cascading optimization

In web development, we use CSS to add style and layout to web pages. However, when multiple style rules are applied to an element at the same time, the problem of style cascading occurs. In this case, we need to understand how to tune the priority of styles. This article explains some ways to tune style priority and provides specific code examples.

The priority of CSS style cascading is determined by the following factors:

The source of the style sheet: Inline style> Internal style sheet> External style sheet
Speciality of the selector: the higher the specificity of the style rule, the higher the priority
The order of the style rules: the style rules defined later will overwrite the style rules defined first

Below, we will introduce these three factors respectively and provide corresponding code examples.

Source of style sheet

Inline styles are styles written directly in HTML tags and have the highest priority. For example:

<div style="color: red;">This is some text.</div>

The internal style sheet is the style written inside the <style></style> tag, and its priority is higher than the external style sheet. For example:

<head>
    <style>
        p {
            color: blue;
        }
    </style>
</head>
<body>
    <p>This is some text.</p>
</body>

External style sheets are styles introduced by linking to external CSS files, and have the lowest priority. For example:

<head>
    <link rel="stylesheet" href="styles.css">
</head>

Speciality of the selector

The specificity of the selector can be calculated by the following rules:

Inline style: Specificity is 1000
ID selector: specificity is 100
Class selector, attribute selector and pseudo-class selector: Specificity is 10
Element selector And pseudo-element selectors: specificity is 1

Selectors with high specificity have higher priority. For example:

<style>
    p {
        color: red;
    }
    
    #myId {
        color: blue;
    }
    
    .myClass {
        color: green;
    }
</style>

<p>This is some text.</p>
<p id="myId">This is some text.</p>
<p class="myClass">This is some text.</p>

In the above code, the text color of the first <p></p> element is red, and the text color of the second <p></p> element is blue, and the text color of the third <p></p> element is green. Because the ID selector is the most specific.

The order of style rules

When multiple style rules have the same selector and specificity, the style rules defined later will overwrite the style rules defined first. For example:

<style>
    p {
        color: red;
    }
    
    p {
        color: blue;
    }
</style>

<p>This is some text.</p>

In the above code, the text color of the <p></p> element is blue because the style rules defined later override the style rules defined first.

By mastering the source of style sheets, the specificity of selectors, and the order of style rules, we can better control the priority of styles. The above are some methods and corresponding code examples for tuning style priority.

I hope this article will be helpful to you in tuning CSS style cascading!

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