How to inherit css

CSS is the abbreviation of Cascading Style Sheet. It is a language used to describe how HTML documents are presented, including fonts, colors, layout, background and other aspects. In CSS, inheritance is a very important feature, which allows us to design styles for the page more conveniently and efficiently. This article will delve into the inheritance mechanism of CSS.

1. What is CSS inheritance

In CSS, an element can inherit style attributes from its parent element. This means that if we set certain style properties on an element, its descendant elements will automatically inherit these properties. The CSS inheritance mechanism allows us to make the style of the entire web page consistent without having to set styles for each element individually.

For example, we can set a font on the body element and then inherit this font in all descendant elements. The code is as follows:

body {
    font-family: Arial, sans-serif;
}

h1 {
    font-size: 2em;
}

In this example, the h1 element will automatically inherit the font set on the body element, but it also overrides the default font size, setting it to 2em.

2. Inheritable and non-inheritable properties

In CSS, not all properties can be inherited. Typically, inheritable properties are those that affect the appearance of an element's content. For example, fonts, colors, and leading are all inheritable properties because they affect the overall appearance of the web page.

However, some properties cannot be inherited because they describe properties of the element itself. For example, an element's width, height, and positioning are non-inheritable properties because they have no effect on the element's content.

The following are some common inheritable and non-inheritable properties:

Inheritable properties:

• font
• color
• line-height
• text-align
• margin
• padding

Non-inheritable properties:

• width
• height
• position
• top
• right
• bottom
• left

It should be noted that not all the same properties are inheritable properties. For example, the background color of an element is an inheritable property, but the background image is a non-inheritable property.

3. Inherited priority

In CSS, inherited styles can be overridden or overridden by descendant elements. This is because when there are multiple style rules for an element, CSS uses a cascading approach to determine the final style of the element.

There are certain rules for the priority of CSS cascading. The following are the rules for CSS cascading priority, ordered from high to low priority:

1. Styles set directly through the style attribute have the highest priority and will override any other styles.
2. The more specific the selector, the higher the priority. For example, ID selectors have higher priority than class selectors, while tag selectors have the lowest priority.
3. Styles that appear multiple times with the same selector will be cascaded according to the order in which they appear in the style sheet, and later styles will overwrite previous styles.
4. Inherited styles have the lowest priority and can be overridden by direct styles of descendant elements.

Therefore, when we use the same inherited properties in multiple style rules, we need to consider their priority. If a descendant element changes the inherited style, it will override the previously specified inheritance rules. We can use the !important keyword to force override other styles, but it will break the maintainability of CSS.

4. Best Practices for Using Inheritance

Using inheritance can effectively reduce the amount of style code, but excessive use of inheritance may make the code more difficult to understand and maintain. The following are best practices for using inheritance:

1. Use inheritance only when necessary. For example, when applying common styles to elements of the same type, it is more convenient to use inheritance than to set the style directly on each element.
2. Use inheritable properties. Use inheritance only on properties that need to apply to all descendants.
3. Understand the priority relationship of inheritance. Correctly understand the priority relationship of inheritance to avoid priority confusion.
4. Avoid overuse of the !important keyword. It breaks the maintainability of CSS and is recommended to be used only when necessary.

Summary

Inheritance is one of the important features in CSS, which allows us to design styles for the page more conveniently and efficiently. When using inheritance, you need to understand the difference between inheritable and non-inheritable properties, as well as the priority relationship of inheritance. At the same time, you need to follow best practices and avoid overuse of inheritance and !important keywords to make CSS code easier to understand and maintain.

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