Several ways to avoid duplication in CSS

CSS (Cascading Style Sheets) is a technology used for web page layout. It can define the style, layout and appearance of web pages. In our daily work, we often encounter situations where we need to add different style sheets to different web pages, and at this time we often encounter the problem of CSS duplication. This article will introduce several methods of CSS non-duplication to help developers better manage style sheets and improve work efficiency.

1. Use the ID selector

The ID selector is one of the most unique and specific selectors in CSS. ID selectors can be used to style individual elements, and each ID name should be unique within a document. This means that if we want to set a unique style on a page, and this style can only be applied to one element, it is best to use an ID selector to ensure that there are no duplicates.

For example, if we want to add styles to a specific element in the page, we can use the following code:

#unique_el {
  background-color: #f2f2f2;
  border: 1px solid #ccc;
  padding: 10px;
}

Where, "unique_el" is a unique ID name, and not Duplicate IDs from other elements on the page.

2. Use class selectors

Class selectors are another selector type commonly used in CSS. Unlike ID selectors, a class name can be used multiple times in a document. This makes class selectors an important tool for working with a group of related elements.

For example, if we want to define a class with red text in the style sheet, we can use the following code:

.red-text {
  color: red;
}

Then, add the class attribute to the element that needs to be set to red text:

<p class="red-text">这段文字是红色的。</p>

The advantage of this method is that you can set the same style for one or more elements, and it is easy to understand and maintain. The disadvantage is that you need to add extra class attributes in the HTML code, and you need to be careful not to repeatedly define class names.

3. Use the attribute selector

The attribute selector is a very flexible selector that can select elements that need to be styled based on their attributes. For example, we can use attribute selectors to select form input elements with specific attribute values, as shown below:

input[type="text"] {
  background-color: #f2f2f2;
  border: 1px solid #ccc;
  padding: 5px;
}

In the above code, we use the attribute selector "[type='text']" to Select the text input box and set its background color, border, and padding. The benefit of this approach is that selection can be made based on the attributes of any element, regardless of the name or position of the element itself. The disadvantage is that attribute selectors may affect other attributes of the element, so you need to be careful.

4. Use inheritance

"Inheritance" in CSS means that child elements inherit certain style attributes of their parent elements. For example, if we set the text color of a

element containing text content to red, then the text of all child elements of this element will inherit this color value.

Using inheritance can avoid repeatedly defining the same style, thereby reducing the amount of code. At the same time, inheritance can also make the appearance of the page more unified, making it easier to maintain.

However, the disadvantage of inheritance is that not all style properties can be inherited. Therefore, when using inheritance, you need to select attributes that can be inherited while avoiding unnecessary repeated definitions.

To sum up, CSS non-duplication is a skill that a web developer must master. Whether we use ID selectors, class selectors, attribute selectors, or avoid repeatedly defining styles through inheritance, it can help us better manage style sheets, improve code efficiency, and thus focus more on achieving business needs.

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